IRLF 


B    3    TDM 


CHEMISTRY 
AND   ITS   RELATIONS   TO   DAILY   LIFE 


THE  MACMILLAN  COMPANY 

NEW  YORK    •    BOSTON   •    CHICAGO   •    DALLAS 
ATLANTA   •    SAN    FRANCISCO 

MACMILLAN  &  CO.,  LIMITED 

LONDON    •    BOMBAY   •    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  LTD. 

TORONTO 


JUSTUS  VON  LIEBIG.     1803-1873. 

The  father  of  Agricultural  Chemistry.    He  was  the  first  to  teach 
rational  basis  for  fertilizing  the  land. 


CHEMISTRY 

AND  ITS  RELATIONS  TO  DAILY  LIFE 


A   TEXTBOOK  FOR   STUDENTS 

OF   AGRICULTURE   AND   HOME   ECONOMICS 

IN  SECONDARY  SCHOOLS 


BY 
LOUIS    KAHLENBERG 

PROFESSOR   OF   CHEMISTRY   AND    DIRECTOR   OF   THE    COURSE    IN    CHEMISTRY 
IN   THE    UNIVERSITY   OF   WISCONSIN 

AND 

EDWIN    B.   HART 

PROFESSOR   OF    AGRICULTURAL   CHEMISTRY    AND    CHEMIST   TO   THE    AGRICULTURAL 
EXPERIMENT   STATION   IN   THE   UNIVERSITY   OF   WISCONSIN 


gorfe 

THE   MACMILLAN   COMPANY 
1913 

All  rights  reserved 


COPYRIGHT,  1913, 
BY  THE  MACMILLAN  COMPANY. 


Set  up  and  electrotyped.     Published  June,  1913. 


Noroiooti 

J.  S.  Gushing  Co.  —  Berwick  &  Smith  Co. 
Norwood,  -Mass.,  U.S.A. 


PREFACE 

THIS  book  is  intended  to  represent  a  year's  work  for 
students  of  agriculture  and  home  economics  in  secondary 
schools.  The  aim  has  been  to  make  the  subject  matter 
thoroughly  practical  in  character  and  to  present  it  in  an 
interesting  and  simple  way  so  that  the  student  may  grasp 
it.  At  the  same  time,  the  delineation  has  been  made  on 
sound  scientific  lines,  and  it  will  require  patient  and  con- 
tinuous application  on  the  part  of  the  student  to  accomplish 
the  work  intelligently.  Useful  facts  have  naturally  been 
placed  in  the  foreground,  and  no  more  theory  has  been 
presented  than  necessary.  Chemical  formulas  have  been  in- 
troduced to  some  extent,  but  merely  as  an  aid  in  expressing 
facts  in  simple,  compact,  and  convenient  form.  Atomic  and 
molecular  theories  have  not  been  presented,  for  they  are  not 
calculated  to  aid  students  at  this  stage  of  advancement. 
While  the  book  is  not  intended  as  a  preparatory  course  for 
colleges,  yet  those  who  have  completed  it  successfully  will 
doubtless  have  gained  information  and  sound  scientific 
training  which  will  compare  favorably  with  that  received  in 
the  pursuit  of  courses  usually  taken  in  preparatory  schools. 

The  laboratory  experiments  detailed  in  Chapter  XXI  are 
to  be  performed  by  the  student  in  connection  with  the  study 
of  each  of  the  preceding  chapters.  The  teacher  should  super- 
vise this  work  carefully  and  require  the  student  to  keep  neat, 
accurate  records  in  a  notebook.  At  the  end  of  Chapter 
XXII  are  given  lists  of  apparatus  and  chemicals  that  will 
be  needed.  Addresses  of  a  few  well-known  firms  from  whom 

V 

265529 


vi  PREFACE 

such  supplies  may  be  obtained  have  also  been  furnished  for 
the  convenience  of  the  teacher. 

The  questions  at  the  end  of  each  chapter  will  help  in 
reviewing  the  salient  points  of  that  chapter.  The  teacher 
will,  of  course,  raise  many  additional  questions,  especially  in 
connection  with  the  laboratory  exercises,  upon  which  special 
stress  should  be  laid. 

While  this  book  is  primarily  intended  as  a  textbook  to 
be  used  by  pupils  in  schools  under  the  supervision  of  a 
teacher,  there  are  doubtless  many  others  who  will  find  it 
helpful  as  a  volume  of  general  information  for  home  reading 
and  study.  Any  corrections  or  suggestions  that  may  be  use- 
ful in  preparing  future  editions  will  be  gratefully  received. 

THE   AUTHORS. 

MADISON,  WISCONSIN, 
February  20,  1913. 


CONTENTS 


CHAPTER 
I. 

II. 
III. 


IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

XII. 

XIII. 

XIV. 

XV. 

XVI. 

XVII. 

XVIII. 

XIX. 

XX. 

XXI. 

XXII. 

INDEX 


GENERAL  FUNDAMENTAL  CONSIDERATIONS 

THE  COMPOSITION  AND  USES  OF  WATER  . 

HYDROGEN,  OXYGEN,  HYDROGEN  PEROXIDE,  AND 
OZONE  

THE   AIR,  NITROGEN,  NITRIC  ACID,  AND   AMMONIA 

ACIDS,  SALTS,  BASES,  AND  CHEMICAL  FORMULAS     . 

THE  HALOGENS 

SULPHUR,  PHOSPHORUS,  ARSENIC,  ANTIMONY,  AND 
BISMUTH 

BORON  AND  SILICON      . 

CARBON  AND  ITS  COMPOUNDS 

THE  METALS  OF  THE  ALKALIES  AND  THE  ALKALINE 
EARTHS  

ALUMINUM,  THE  HEAVY  METALS,  AND  THEIR  IM- 
PORTANT ALLOYS 

PAINTS,  OILS,  AND  VARNISHES     ..... 

LEATHER,  SILK,  WOOL,  COTTON,  AND  RUBBER 

THE  SOIL 

COMMERCIAL  FERTILIZERS 

FARM  MANURE 

PLANT  LIFE  AND  WHAT  IT  PRODUCES 

THE  ANIMAL  AND  ITS  FEED 

HUMAN  AND  ANIMAL  FOODS        ..... 

MILK  AND  ITS  PRODUCTS 

POISONS  FOR  FARM  AND  ORCHARD  PESTS 

PRACTICAL  LABORATORY  EXPERIMENTS 


PAGE 
1 


22 

30 
41 
52 

59 
74 
81 

118 

140 
171 
179 
191 
214 
229 
238 
255 
269 
291 
307 
321 

381 


vii 


CHEMISTRY  AND  ITS  RELATIONS 
TO  DAILY  LIFE 

i 

CHAPTER  I 
GENERAL  FUNDAMENTAL  CONSIDERATIONS 

ANIMALS,  plants,  water,  rocks,  soil,  and  the  air  are  the 
things  that  make  up  the  earth  and  its  atmosphere.  These 
have  been  the  subject  of  study  since  earliest  times,  and  a 
considerable  amount  of  knowledge  has  consequently  been 
gathered  concerning  living  beings,  plants,  and  animals,  and 
their  relations  to  water,  the  air,  and  the  solid  portions  of  the 
earth's  crust.  All  of  this  knowledge  is  the  result  of  observa- 
tion by  means  of  our  senses,  sight,  hearing,  smell,  taste,  touch, 
and  experience  of  changes  of  temperature.  For  many  cen- 
turies the  results  of  such  observations  have  gradually  been 
collected,  corrected,  and  recorded  in  books  and  manuscripts. 
Such  carefully  gathered  and  systematically  arranged  knowl- 
edge is  called  Science.  In  other  words,  science  is  systematized 
knowledge  resulting  from  careful  observation  made  with  a 
definite  purpose  in  view.  The  opinions  that  men  have  formed 
as  a  result  of  reflection,  that  is,  thinking  over  such  observa- 
tions, also  form  a  part  of  science,  and  indeed  such  opinions 
are  commonly  recorded  in  scientific  books.  Now  it  is  clear 
that  these  opinions  may  differ  somewhat,  and  sometimes  they 
differ  quite  widely,  especially  if  the  observations  have  been 
made  with  insufficient  care,  or  if  not  enough  observations 
have  been  made  to  warrant  drawing  a  fairly  safe  conclusion. 


2  CHEMISTRY  AND  DAILY  LIFE 

The  opinions  then  change  from  time  to  time  as  better  obser- 
vations and  more  of  them  accumulate.  Consequently  the 
opinions,  that  is  to  say,  the  theories  or  theoretical  views,  are 
the  changeable,  the  ephemeral  part  of  science,  though,  to 
be  sure,  the  observations  too  may  be  improved  and  multi- 
plied, as  already  stated. 

The  Greek  philosopher  Aristotle  (384-322  B.C.)  taught  that 
water,  air,  earth,  and  fire  are  the  elements  of  which  all  other 
things  are  composed,  and  indeed  this  view  was  held  for  many 
centuries.  Even  now  in  literature,  in  the  descriptions  of 
storms,  conflagrations,  and  the  like,  we  sometimes  still  speak 
of  the  "  battle  of  the  elements."  Such  allusions,  to  be  sure, 
are  now  only  figures  of  speech,  for  the  elements  of  the  ancient 
Greeks  are  not  at  all  the  elementary  constituents  of  which 
things  are  composed.  In  fact  a  careful  study  of  all  of  the 
available  materials  on  the  earth,  including  the  atmosphere 
has  shown  that  there  are  about  eighty  substances  that  cannot 
be  made  from  other  substances  and  cannot  themselves  be  resolved 
into  anything  else.  For  example,  iron  is  one  of  these  eighty 
substances.  No  one  has  ever  been  able  to  make  iron  from 
other  substances  that  do  not  already  contain  it;  neither 
has  it  been  possible  to  produce  other  substances  from  iron 
alone.  Iron  is  consequently  spoken  of  as  an  element  or  an 
elementary  substance.  Similarly  carbon  is  an  element. 
This  substance  we  have  in  almost  pure  form  in  the  diamond, 
graphite,  and  the  better  grades  of  charcoal. 

In  Table  1  given  on  the  opposite  page  is  a  list  of  the 
chemical  elements  and  the  abbreviations  or  symbols  by 
means  of  which  they  are  very  often  designated. 

In  the  list  there  are  many  commonly  known  substances. 
These  have  been  designated  by  means  of  heavy  type. 
These  more  common  elements  number  only  about  twenty- 
five,  and  indeed  the  most  important  elements  are  scarcely 


GENERAL   FUNDAMENTAL  CONSIDERATIONS 


TABLE   1 

THE  CHEMICAL  ELEMENTS  AND  THEIR  SYMBOLS 


ELEMENT 

SYMBOL 

ELEMENT 

SYMBOL 

Aluminum 

Al 

Neodymium 

Nd 

Antimony 

Sb 

Neon 

Ne 

Argon 

A 

Nickel 

Ni 

Arsenic 

As 

Niton  (radium 

Barium 

Ba 

emanation) 

Nt 

Bismuth 

Bi 

Nitrogen 

N 

Boron 

B 

Osmium 

Os 

Bromine 

Br 

Oxygen 

0 

Cadmium 

Cd 

Palladium 

Pd 

Caesium 

Cs 

Phosphorus 

P 

Calcium 

Ca 

Platinum 

Pt 

Carbon 

C 

Potassium 

K 

Cerium 

Ce 

Praseodymium 

Pr 

Chlorine 

Cl 

Radium 

Ra 

Chromium 

Cr 

Rhodium 

Rh 

Cobalt 

Co 

Rubidium 

Rb 

Columbium 

Cb 

Ruthenium 

Ru 

Copper 

Cu 

Samarium 

Sa 

Dysprosium 

Dy 

Scandium 

Sc 

Erbium 

Er 

Selenium 

Se 

Europium 

Eu 

Silicon 

Si 

Fluorine 

F 

Silver 

Ag 

Gadolinium 

Gd 

Sodium 

Na 

Gallium 

Ga 

Strontium 

Sr 

Germanium 

Ge 

Sulphur 

S 

Glucinum 

Gl 

Tantalum 

Ta 

Gold 

Au 

Tellurium 

Te 

Helium 

He 

Terbium 

Tb 

Hydrogen 

H 

Thallium 

Tl 

Indium 

In 

Thorium 

Th 

Iodine 

I 

Thulium 

Tm 

Iridium 

Ir 

Tin 

Sn 

Iron 

Fe 

Titanium 

Ti 

Krypton 

Kr 

Tungsten 

W 

Lanthanum 

La 

Uranium 

U 

Lead 

Pb 

Vanadium 

V 

Lithium 

Li 

Xenon 

Xe 

Lutecium 

Lu 

Ytterbium 

Magnesium 

Mg 

(Neoytterbium) 

Yb 

Manganese 

Mn 

Yttrium 

Yt 

Mercury 

Hg 

Zinc 

Zn 

Molybdenum 

Mo 

Zirconium 

Zr 

4  CHEMISTRY  AND   DAILY  LIFE 

more  than  a  dozen.  All  known  substances,  natural  or  arti- 
ficial, —  whether  they  exist  in  the  atmosphere,  as  part  of  the 
earth's  crust,  in  natural  waters,  as  parts  of  plants  or  animals, 
or  indeed  as  parts  of  the  heavenly  bodies,  —  are  composed  of 
one  or  more  of  the  chemical  elements  mentioned  in  Table  1.  It 
is  the  task  of  the  chemist  to  study  the  composition  of  sub- 
stances, to  build  up  new  substances  from  given  ones,  and 
again  to  tear  down  complex  substances,  thus  resolving  them 
into  simpler  bodies.  Whenever  a  change  takes  place  in  which 
new  substances  are  formed,  the  change  is  called  a  chemical 
change.  So,  for  example,  when  a  piece  of  paper  is  burned, 
entirely  new  substances  are  formed  ;  again,  when  iron  rusts,  a 
new  substance,  the  rust,  is  produced.  These  are  examples  of 
chemical  change.  The  chemist,  however,  studies  not  only  the 
new  products  that  are  produced  from  other  substances,  but 
he  also  takes  into  consideration  the  means  employed  to  cause 
the  chemical  change  to  take  place.  Then  again  he  studies 
the  rate  with  which  the  change  proceeds,  ascertaining  also 
whether  all  or  only  part  of  the  substance  has  finally  been 
transformed.  The  various  conditions  that  affect  the  rate 
with  which  the  change  takes  place,  and  the  accompaniments 
of  the  change  such  as  alterations  of  temperature,  volume, 
evolution  of  light,  electricity,  etc.,  are  also  carefully  studied. 
The  sum  total  of  all  these  observations,  systematically  arranged, 
constitutes  the  science  of  chemistry.  It  touches  every  walk  of 
life,  for  wherever  there  is  anything  material,  that  is  to  say, 
wherever  there  is  anything  that  we  can  touch,  hear,  see,  taste, 
or  smell,  we  have  an  object  with  which  chemistry  is  con- 
cerned. In  fact  chemical  changes  are  continually  going  on 
about  us.  The  food  we  eat  is  chemically  transformed  into 
the  various  tissues  of  our  bodies,  and  these  in  turn  are  acted 
upon  by  oxygen  derived  from  the  air  we  breathe,  and  thus 
oxidized  into  simpler  substances  which  are  in  turn  eliminated 


GENERAL   FUNDAMENTAL  CONSIDERATIONS       5 

by  means  of  the  breath,  the  bowels,  the  kidneys,  and  the 
skin.  Thus  our  very  lives  depend  upon  a  series  of  chemical 
changes.  Similarly  the  lives  of  all  animals  and  plants  depend 
upon  chemical  transformations  of  the  material  they  take  into 
their  bodies,  the  products  of  such  chemical  changes  being 
finally  eliminated  as  the  organism  lives.  But  chemical 
changes  are  continually  in  progress  in  inanimate  things,  also. 
Thus  the  soil  and  rocks  are  being  acted  upon  continually  by 
water  and  the  gases  of  the  atmosphere,  new  products  result- 
ing, which  are  more  or  less  soluble  in  the  water.  Materials 
from  these  solutions  are  taken  up  by  the  rootlets  of  trees 
and  other  plants.  Furthermore  as  natural  waters  are  drunk 
by  animals,  some  of  these  soluble  substances  are  absorbed 
by  the  membranes  of  the  digestive  tracts  of  the  organisms 
and  used  in  building  up  new  tissues. 

Many  industrial  processes  and  common  operations  in  the 
household  and  on  the  farm  depend  upon  chemical  changes, 
and  it  is  the  purpose  of  this  book  to  study  some  of  the  more 
important  of  these.  It  should  be  stated  here,  however,  that 
whenever  a  change  takes  place  which  is  not  accompanied  by  a 
formation  of  one  or  more  new  substances,  the  change  is  called  a 
physical  change.  Thus  when  a  piece  of  gold  is  heated,  it  still 
remains  gold  and  there  is  no  change  except  a  change  of  tem- 
perature and  of  volume.  Again,  when  a  glass  rod  is  electrified 
by  rubbing  it  with  a  silk  rag,  neither  the  substance  of  the  rag 
nor  that  of  the  glass  is  altered.  These,  then,  are  typical 
examples  of  physical  change.  '  Physical  changes  are  exceed- 
ingly numerous,  and  they  very  frequently  occur  without  any 
accompanying  chemical  change.  On  the  other  hand,  chem- 
ical changes  practically  never  occur  without  accompanying  phys- 
ical changes,  for  the  formation  of  new  substances  is  generally 
accompanied  by  increase  or  decrease  of  volume,  rise  or  fall  of 
temperature,  and  frequently  by  evolution  of  light,  electricity, 


6  CHEMISTRY  AND  DAILY  LIFE 

or  still  other  forms  of  energy.  So  when  a  piece  of  magnesium 
is  burned  in  the  air,  a  white  powder,  magnesium  oxide,  is 
formed,  and  this  is  more  bulky  than  the  original  magnesium  ; 
furthermore,  during  the  burning  of  the  metal  both  light  and 
heat  are  evolved. 

A  glance  at  Table  1  shows  that  the  elements  may  be  roughly 
divided  into  two  great  classes,  the  metals  and  the  non-metals. 
It  is,  however,  not  possible  to  make  a  perfectly  sharp  division 
into  these  two  classes,  for  there  are  some  elements  that 
exhibit  properties  which  partake  of  the  nature  of  both  the 
metal  and  the  non-metal.  Thus  it  would  be  easy  to  class 
such  elements  as  copper,  silver,  iron,  gold,  mercury,  zinc,  and 
sodium  as  typical  metals ;  and  again,  it  would  be  simple  to 
place  such  elements  as  sulphur,  oxygen,  carbon,  chlorine,  and 
phosphorus  as  non-metals.  But  elements  like  arsenic  and 
antimony,  for  example,  while  possessing  metallic  luster  and 
also  some  of  the  chemical  properties  of  typical  metals,  are 
nevertheless  brittle  and  in  their  chemical  behavior  also 
otherwise  closely  related  to  the  non-metals.  Such  elements 
as  partake  of  the  nature  of  both  the  metals  and  non-metals  are 
sometimes  called  metalloids.  They  are  in  reality  a  transition 
between  the  metals  and  the  non-metals. 

When  a  substance  consists  of  two  or  more  elements,  it  is  called 
a  compound.  Thus  oxide  of  magnesium  is  a  compound,  for 
it  is  formed  by  the  union  of  oxygen  and  magnesium.  Lime 
is  a  compound,  for  it  contains  the  metal  calcium  and  oxygen. 
Sugar  is  a  compound,  for  it  consists  of  oxygen,  hydrogen,  and 
carbon.  Water  is  a  compound,  for  it  is  composed  of  oyxgen 
and  hydrogen.  As  water  is  the  most  common  compound  on 
the  earth,  and  as  the  elements  that  compose  it  are  also  of  vast 
importance  in  all  plant  and  animal  life,  the  chemistry  of  water 
'will  be  our  first  object  of  study. 


GENERAL   FUNDAMENTAL  CONSIDERATIONS       7 

QUESTIONS 

1.  What  is  science? 

2.  What  is  a  fact? 

3.  What  is  a  theory?  t 

4.  Mention  the  things  which  the  ancient  Greeks  called  elements. 

5.  What  is  a  chemical  element  as  regarded  at  present? 

6.  About  how  many  chemical  elements  are  there,  and  how  may 
they  be  classified? 

7.  What  is  a  compound?    Give  three  examples. 

8.  What  is  a  physical   change?    Give  three  illustrations  of 
physical  changes. 

9.  What  is  a  chemical  change  ?    Give  four  examples  of  chemical 
change. 

10.  Do  chemical  changes  occur  with  or  without  accompanying 
physical  changes?  Explain  your  answer  by  means  of  a  specific 
illustration. 


FIG.  1.— 


CHAPTER  II 

THE   COMPOSITION   AND   USES 
OF   WATER 

WATER  is  a  compound  of  the  ele- 
ments oxygen  and  hydrogen.    When  an 
electric  current  is  passed  through  water 
in  an  apparatus  like  that  shown  in  Fig. 
1,  oxygen  is  evolved  on  the  positive 
plate  and  hydrogen  on  the  negative 
plate ;  and  it  is  found  that  the  volume 
of  the  oxygen  is  one  half  that  of  the 
hydrogen.    That  is  to  say,  when  water 
is  decomposed  by  electrolysis,  one  volume 
of  oxygen  and  two  volumes  of  hydrogen 
are  formed.     Now  one  volume  of  oxy- 
gen weighs  very  nearly  sixteen  times 
as  much  as  an  equal  volume  of  hydro- 
gen; consequently  the  vol- 
ume of  oxygen  produced  in 
the    electrolysis    of    water 
weighs  eight  times  as  much 
as  the  two  volumes  of  hy- 
drogen that  are  liberated. 

By  taking  two  volumes 
of  hydrogen  and  one  vol- 
ume   of     oxygen,     mixing 
them,  and  igniting  the  mix- 
The  electrolysis  of  water.       ture  with  a  flame  or  an  elec- 


THE   COMPOSITION   AND  USES   OF  WATER         9 

trie  spark,  as,  for  example,  in  the  apparatus  in  Fig.  2,  water 
is  formed  and  no  hydrogen  or  oxygen  is  left  uncombined. 
Thus  the  qualitative  and  quantitative  composition  of  water 
is  clearly  established. 


FIG.  2. —  Explosion  of  a  mixture  of  hydrogen  and  oxygen. 

Though  water  is  extremely  abundant,  it  never  is  found 
in  the  pure  state  in  nature.  The  waters  of  the  oceans  and 
many  inland  seas  are  salty.  Lake  water  and  the  waters  of 
brooks  and  rivers,  as  well  as  those  of  springs  and  wells,  always 
contain  more  or  less  solid  saline  material  which  has  been 
dissolved  by  the  water  while  in  contact  with  the  soil  and  rocks, 
On  evaporating  such  saline  waters,  all  of  the  solids  remain 
behind  as  a  residue.  Thus  when  sea  water  or  well  water  is 
placed  in  a  dish  and  allowed  to  evaporate  either  slowly  at 


10  CHEMISTRY  AND  DAILY  LIFE 

ordinary  temperature  or  upon  boiling,  there  remains  a 
residue  of  the  material  that  was  dissolved  in  the  water.  By 
evaporating  several  gallons  of  water  one  may  obtain  a  suffi- 
cient amount  of  such  dissolved  matter  to  make  a  chemical 
analysis  of  it  and  thus  determine  its  exact  nature.  Thus 
the  dissolved  matters  in  many  terrestrial  waters  have  been 
analyzed.  Both  the  nature  and  the  amounts  of  the  saline  mat- 
ters contained  in  a  water  are  determined  by  the  character  of 
the  rocks  over  which  the  water  has  coursed.  The  purest  natural 
water  is  rain  water.  It  contains  no  mineral  matter,  except 
such  small  quantities  of  dust  as  have  been  carried  into  the  air 
by  the  wind  and  then  washed  down  by  the  descending  drops. 
After  it  has  rained  awhile  and  the  air  has  been  well  washed, 
the  rain  that  falls  consists  of  much  purer  water,  but  it  always 
contains  air  dissolved  in  it  and  not  infrequently  nitrogenous 
compounds  like  nitrites  and  nitrates  of  ammonium,  which 
are  formed  as  the  lightning  flashes  through  the  air.  By  boil- 
ing water  and  condensing  the  vapors  a  fairly  pure  water,  com- 
monly called  distilled  water,  is  obtained.  Figure  3  shows  a 
simple  apparatus  for  producing  distilled  water.  Every  distill- 
ing apparatus  consists  of  a  retort,  a  condenser,  and  a  receiver. 
In  Fig.  3  these  are  indicated  by  A,  B,  and  C,  respectively. 

The  heat  of  the  sun  causes  water  to  evaporate  continually 
from  the  surface  of  the  oceans,  lakes,  rivers,  and  moist  soil. 
This  moisture  is  then  condensed  on  reaching  cooler  layers 
of  air,  forming  clouds,  fogs,  dew,  and  rain.  The  rain  water 
permeates  the  soil,  dissolves  portions  of  it,  and  gradually 
makes  its  way  into  brooks,  rivers,  lakes,  and  the  sea.  Then 
evaporation  again  goes  on  from  the  surfaces  of  these  bodies 
of  water,  condensation  again  takes  place,  rain  falls,  and  so 
the  ceaseless  round  continues  as  long  as  the  sun  furnishes 
the  needed  energy.  Thus  it  is  clear  that  all  water  power  is 
really  derived  from  the  sun.  But  not  all  of  the  water  is  thus 


THE   COMPOSITION   AND  USES  OF  WATER       11 

evaporated  or  carried  into  the  sea.  Some  of  it,  though,  to  be 
sure,  but  a  relatively  small  portion,  is  taken  from  the  soil  by 
the  rootlets  of  plants,  and  again  a  certain  amount  is  drunk 
by  animals.  Without  water,  plants  and  animals  cannot  live. 
Indeed  the  bodies  of  all  plants  and  animals  contain  from  fifty  to 
ninety  per  cent  of  water  by  weight.  This  water,  to  be  sure,  is 
more  or  less  firmly  combined  with  the  other  materials  that  en- 
ter into  the  composition  of  the  plant  and  animal  bodies.  From 


FIG.  3.  —  Tho  distillation  of  water. 

the  latter  it  may  be  obtained  by  desiccation.  That  the  tis- 
sues of  plants  and  animals,  soils,  and  not  infrequently  min- 
erals, rocks,  and  various  artificial  salts  like  blue  vitriol, 
epsom  salts,  etc.,  contain  water  may  readily  be  shown  by 
gently  heating  a  small  portion  of  the  substance,  about  the 
size  of  a  small  nut,  in  a  test  tube  as  shown  in  Fig.  4.  The 
water  set  free  condenses  in  drops  on  the  upper  cooler  portions 
of  the  test  tube.  In  such  experiments  one  soon  discovers 
that  some  compounds  retain  the  water  much  more  tenaciously 
than  others,  for  while  very  slight  warming  suffices  to  liberate 
the  water  in  some  instances,  other  substances  need  to  be 
heated  even  to  redness  before  the  water  is  set  free.  So,  for 


12  CHEMISTRY  AND   DAILY  LIFE 

example,  when  grass,  a   piece   of    carrot,  or   lean   meat   is 
gently  heated  in  a  test  tube,  water  is  readily  formed  in  drops 

on  the  upper  cooler  parts  of  the 
tube.  To  drive  the  water  out 
of  an  old  piece  of  mortar  or  con- 
crete would,  however,  require  a 
much  higher  temperature.  In- 
deed, it  would  be  necessary  to 
heat  the  substance  to  dull  red- 
ness. 

The  amount  of  water  contained 
in  plants  and  animals  is  usually 
high.     But    different    organisms 
frequently  contain  quite  different 
FIG.  4. -Testing^  substance      quantities  of  water,  the  amount 

of  which  is  commonly  found  by 

weighing  the  plant  or  animal  substance  and  then  drying 
it  to  constant  weight  at  the  boiling  point  of  water,  namely, 
100°  C.  The  difference  between  the  original  weight  and 
that  of  the  dried  residue  represents  the  moisture  content. 
In  this  way  it  has  been  found  that  the  leaves  of  herbaceous 
plants  contain  from  60  to  80  per  cent  water;  potatoes, 
juicy  fruits,  and  succulent  plants  contain  from  85  to  95  per 
cent  water;  and  algae  and  other  aquatic  plants  may  even 
contain  as  much  as  98  per  cent.  On  the  other  hand,  wood 
commonly  contains  only  from  44  to  55  per  cent  water,  and 
many  dry  seeds  contain  much  less.  Dry  grass  seed,  for  ex- 
ample, contains  only  about  15  per  cent  water.  The  dried 
residue  of  the  plant  substance  may  be  burned,  whereupon 
there  remains  the  ash,  which  represents  the  mineral  matter 
in  the  plant.  The  combustible  portion,  which  has  been  de- 
stroyed, is  the  so-called  organic  matter  of  the  plant.  It  is 
oxidized  and  largely  volatilized  in  the  process  of  burning 


THE   COMPOSITION  AND  USES   OF  WATER       13 

(see  combustion),  there  being  formed  gaseous  substances  like 
carbon  dioxide,  water  vapor,  nitrogen,  and  ammonia.  The 
amount  of  ash  found  in  different  plant  substances  also  varies 
considerably.  Computed  on  the  dried  material,  for  example, 
oak  wood  contains  about  0.48  per  cent  ash,  rye  straw  4.46 
per  cent,  rye  grain  2.09  per  cent,  tobacco  leaves  17.16  per 
cent,  potato  leaves  8.58  per  cent,  potatoes  3.79  per  cent. 
In  general  the  leaves  of  plants  contain  more  ash  than  the  other 
parts.  The  ash  of  different  plants  has  different  composition, 
which  fact  will  be  discussed  more  fully  later. 

The  water  content  of  animals  also  varies  considerably. 
The  following  table  indicates  the  amount  of  water  contained 
in  a  few  of  the  common  animals,  the  entire  body  being 

considered : 

TART  F    2 

ANIMAL  WATER  CONTENT 

Fat  ox 45.5  per  cent 

Fat  calf 63  per  cent 

Fat  pig 41  per  cent 

Lean  pig 55  per  cent 

Fat  sheep 43  per  cent 

Lean  sheep 51  per  cent 

Chicken  flesh 74  per  cent 

Goose  flesh .42  per  cent 

Turkey  flesh 55  per  cent 

Brook  trout 78  per  cent 

White  fish 70  per  cent 

Lobster  (exclusive  of  shell) 79  per  cent 

Oyster  (exclusive  of  shell) 81  per  cent 

Table  3  presents  the  water  content  of  various  parts  of  an  ox. 

PART  WATER  CONTENT 

Brain 80  per  cent 

Heart 63  per  cent 

Muscle  of  the  loin  .  ' 62  per  cent 

Kidney ' 76  per  cent 

Liver 71  per  cent 

Sweet  breads 71  per  cent 

Lungs 80  per  cent 


14  CHEMISTRY  AND   DAILY  LIFE 

From  these  data  it  is  apparent  that  considerably  over  half 
of  the  weight  of  animal  tissues  consists  of  water.  It  should 
be  borne  in 'mind,  however,  that  this  water  is  more  or  less 
tightly  combined  with  the  other  constituents  of  the  tissues. 
By  expelling  the  water  in  the  process  of  drying,  these  combi- 
nations are  ruptured,  the  water  being  thus  liberated. 

Now  as  human  beings  subsist  on  food  that  comes  from 
animals  and  plants,  it  is  clear  that  the  human  body  derives 
from  such  food  a  considerable  amount  of  the  water  it  needs. 
This,  however,  is  not  sufficient,  for  drinking  water  is  required 
in  addition.  Chemically  pure  water  is  not  good  drinking  water. 
Freshly  distilled  water,  obtained  by  careful  distillation  of 
spring  or  artesian  well  water,  is  insipid  and  flat  to  the  taste, 
chiefly  because  by  the  process  of  boiling  during  distillation 
the  air  which  was  dissolved  in  the  water  has  been  expelled. 
For  the  same  reason  water  that  has  been  boiled  and  then  cooled 
without  sufficient  opportunity  to  become  thoroughly  aerated 
again  has  a  flat  taste.  Many  natural  spring  waters  and  well 
waters  are  excellent  drinking  waters,  though  they  always  con- 
tain solid  matter  in  solution  that  comes  from  the  rocks  and 
soils  over  which  the  water  has  flowed.  The  amount  of  this 
mineral  matter  varies  very  greatly  with  the  nature  of  the 
solid  material  with  which  it  has  been  in  contact.  So,  for 
instance,  water  that  has  coursed  over  granite  rocks  only  has  but 
very  little  mineral  matter  in  it,  for  granite  is  but  slightly  soluble 
in  water.  On  the  other  hand,  water  in  limestone  regions  is 
highly  charged  with  mineral  matter,  for  limestone  is  relatively 
readily  soluble  in  water  especially  when  the  latter  contains  carbon 
dioxide,  and  this  is  always  the  case  with  water  that  has  been 
in  contact  with  the  air,  for  the  latter  contains  carbon  dioxide 
(see  air). 

Table  4  gives  the  amount  of  mineral  matter  contained  in  a 
few  typical  natural  waters  in  grams  per  1000  liters.  These 


THE   COMPOSITION  AND  USES  OF  WATER        15 

figures  are  obtained  by  evaporating  a  given  weight  of  water 
to  dryness,  weighing  the  residue,  and  then  computing  the 
amount  of  the  latter  per  1000  liters  of  the  water  taken. 

TABLE   4 

MINERAL  CONTENT  IN 
WATER  FROM  GRAMS  PER  1000  LITERS 

Atlantic  Ocean 35,664 

Indian  Ocean 35,525 

White  Sea 33,118 

Dead  Sea 253,016 

Great  Salt  Lake 302,122 

Lake  Michigan 145 

Vichy  Springs 6,798 

Karlsbad  Springs 6,091 

Artesian  well  at  St.  Petersburg 3,891 

Artesian  well  at  London 834 

Artesian  well  at  Madison,  Wis 371 

Spring  near  Wausau,  Wis 64 

Rhine  River 231 

Nile  River     .     .    ' 142 

It  is  to  be  borne  in  mind  that  the  mineral  matter  dissolved 
in  river  waters  often  varies  materially  according  to  the  time  and 
place  of  taking  the  sample.  The  mineral  content  of  waters  of 
lakes  and  oceans  also  varies  somewhat  with  the  depth  and 
locality.  The  figures  in  Table  4  are  consequently  to  be 
regarded  as  subject  to  certain*  fluctuations.  They  serve, 
however,  to  give  a  general  idea  of  the  amount  of  mineral 
matter  found  in  natural  waters. 

The  mineral  content  of  oceanic  water  and  of  salt  lakes  and 
seas  consists  chiefly  of  common  salt,  and  such  water  is,  of 
course,  not  fit  to  drink.  Spring  and  well  waters  that  contain 
considerable  amounts  of  calcium  salts  (also  often  called  lime 
salts)  in  solution  are  called  hard  waters.  They  may  be 
quite  good  for  drinking  purposes,  but  they  are  not  good  for 
washing  or  steam  boiler  purposes,  for  in  the  boilers  they 
deposit  a  hard  coating  or  scale,  like  that  commonly  found  in 


16  CHEMISTRY  AND   DAILY   LIFE 

an  ordinary  teakettle,  for  example,  and  with  soap  they  form 
no  suds,  but  simply  a  curd,  which  is  in  reality  an  insoluble 
calcium  soap  resulting  from  the  decomposition  of  the  soluble 
soap  employed,  by  the  calcium  salts  in  the  water.  Before 
such  water  can  be  used  for  washing  or  boiler  purposes,  the 
lime  salts  it  contains  must  be  removed.  This  can  be  done 
in  one  of  two  ways :  (1)  by  distilling  the  water,  a  process 
which  on  account  of  the  fuel  required  is  expensive  and  so 
practically  out  of  the  question  for  ordinary  purposes,  and 
(2)  by  throwing  the  lime  salts  out  of  solution  by  adding  some 
other  ingredients  which  will  form  insoluble  compounds  with 
the  lime  in  the  water.  Soluble  salts  which  thus  act  on  the 
lime  salts  and  form  precipitates  with- them  are  often  spoken 
of  as  water  cleansers  or  water  purifiers.  Among  those 
commonly  in  use  are  sodium  carbonate  (also  called  washing 
soda),  borax,  and  sodium  phosphate.  Of  all  of  the  natural 
waters  rain  water  is  by  far  the  best  and  cheapest  for  washing  and 
boiler  purposes.  It  should  be  collected  and  stored  in  clean 
tanks  or  cisterns  to  which  air  has  ready  access.  By  the  use 
of  Portland  cement  (which  see)  it  is  now  an  easy  matter  to 
construct  suitable  reservoirs  for  the  storage  of  rain  water  at 
a  moderate  cost.  Such  cistern  water  when  clean  and  well 
aerated  is  good  drinking  water,  though  its  mineral  content  is 
quite  low,  being  simply  due  to  the  small  amount  of  material 
dissolved  from  the  cement-lined  walls  of  the  cistern. 

Sometimes  spring  water  of  well  water  is  found  to  be  unfit 
to  drink  because  of  the  poisonous  or  otherwise  injurious 
mineral  ingredients  it  contains.  But  such  cases  are  after  all 
quite  rare,  being  in  general  confined  to  excessively  alkaline  or 
strongly  saline  waters.  For  example,  near  copper  deposits 
the  waters  may  contain  a  considerable  amount  of  compounds 
of  that  metal  and  so  be  injurious  to  health.  In  any  case 
ic hen  water  has  a  taste  or  smell  that  causes  suspicion,  it  ought 


THE   COMPOSITION   AND   USES  OF  WATER        17 

to  be  properly  tested  to  ascertain  whether  it  is  potable.  Water  is 
more  frequently  rendered  unfit  to  drink  because  of  contami- 
nation with  plant  or  animal  refuse,  sewage,  disease-producing 


FIG.  5  (a).  — The  kind  of  a  well  into  which  surface  water  will  readily  seep. 


FIG.  5  (6). — An  example  of  how  pollution  may  occur. 

bacteria,  or  other  pathogenic  organisms.  Wherever  there  is 
decaying  animal  or  vegetable  matter  there  microorganisms 
abound,  and  water  contaminated  with  such  material  is  dangerous 


18 


CHEMISTRY  AND   DAILY  LIFE 


to  health.  A  drinking  water  ought  consequently  to  be  ex- 
amined as  to  its  content  of  microorganisms  as  well  as  sub- 
jected to  chemical  tests  before  being  pronounced  safe  for 
drinking  purposes.  Surface  wells  near  human  habitations 
soon  become  contaminated  from  seepage  from  outhouses, 
cesspools,  barnyards,  and  the  like.  It  is  to  be  borne  in 
mind  that  after  all  a  well  is  merely  a  hole  in  the  ground  into 
which  water  from  the  surroundings  tends  to  drain.  Mounding 
up  the  earth  around  the  pump  or  opening  of  the  well,  of 
course,  does  not  prevent  the  water  of  the  soil  in  the  neigh- 
borhood from  getting  into  the  well.  Such  a  mound  at  the 
opening  of  the  well  can  at  best  only  prevent  the  water  that 

is  on  the  surface  of  the 
ground  from  running  into 
the  mouth  of  the  well. 
Typhoid  fever  is  one  of  the 
commonest  and  most  dan- 
gerous diseases  that  may  re- 
sult from  drinking  polluted 
water.  This  disease  is  due 
to  the  bacillus  typhosus, 
which  is  not  infrequently 
present  in  contaminated 
water.  Dysentery  and 
other  intestinal  and  gastric 
disturbances  may  result 
from  the  presence  of  other 
organisms.  //  there  is  no  alternative  but  to  use  water  that  is 
known  to  be  contaminated  for  drinking  purposes,  it  should  first 
be  boiled.  This  destroys  the  organisms  it  contains,  but  the 
water  after  boiling  tastes  flat  as  already  mentioned.  Con- 
taminated water  is  also  frequently  filtered  through  unglazed 
porcelain.  Such  filters  are  commonly  known  as  the  Pasteur 


FIG.  6. 


•Typhoid  bacillus  greatly 
magnified. 


THE   COMPOSITION  AND  USES   OF  WATER        19 


water  filters.     They  remove  nearly  all  of  the  matter  sus- 
pended in  the  water  as  well  as  a  very  large  share  of  the 
organisms  that  are  present. 
But  such  filters  need  to  be 
renewed  frequently,  for  the 
refuse   they    accumulate    in 
their    pores    soon    becomes 
only    an    added    source    of 
danger  toward  further  con- 
tamination.   On  a  large  scale 
water  is  frequently  purified 
by  filtration  through  prop- 
erly   constructed    filters    of 
gravel  or  crushed  rock  and 
sand.     These  too  are  fairly 
efficient  in  removing  danger- 
ous   material    suspended    in 
the    water,    but    they    also 
require  to  be  renewed  from 
time  to  time.    Water  derived 
from  wells  that  are  a  hun- 
dred feet  or  more  deep  has 
obviously  been  well  filtered 
in  coursing  through  the  vari- 
ous strata  to  the  depth  from 
which  it  issues,  and  conse- 
quently such  water  is  practi- 
cally always  free  from  organic 
contaminations.      Deep  well 
water  is  therefore  usually  to 
be     preferred    for     drinking 
purposes. 

Besides  resorting  to  boiling  or  filtration  for  the  purpose  of 


FIG.  7.  —  Pasteur  water  filter. 


20  CHEMISTRY  AND  DAILY  LIFE 

removing  organic  contamination  from  a  potable  water 
supply,  chemical  means  of  purification  may  be  adopted. 
This  always  involves  introducing  some  chemical  substance 
into  the  water,  which  destroys  the  organisms  it  contains. 
For  such  purposes  a  solution  of  sodium  or  calcium  hypo- 
chlorite  (bleaching  powder)  is  not  infrequently  employed, 
especially  in  the  case  of  a  city  water  supply  where  the  water 
in  the  reservoir  and  mains  shows  a  high  bacterial  content. 
It  is  best  to  avoid  the  introduction  of  such  chemicals  into 
drinking  water,  for  these  substances  which  destroy  bacteria 
are  also  deleterious  to  health.  It  is  only  when  the  disease 
germs  are  actually  present  in  the  water  that  such  chemical 
treatment  is  really  justifiable,  for  the  germs  are  far  more 
dangerous  than  the  relatively  small  amounts  of  the  anti- 
septics required  to  kill  them.  An  antiseptic  is  a  chemical 
that  destroys  germs,  or  prevents  or  retards  their  growth,  without 
exerting  a  materially  harmful  effect  upon  the  living  body. 
Antiseptics  therefore  frequently  are  germicides.  These  will  be 
referred  to  again. 

QUESTIONS 

1.  How  may  it  be  shown  that  water  is  a  compound  of  oxygen 
and  hydrogen  ? 

2.  In  what  proportions  by  weight  do  these  elements  occur  in 
water  ?    In  what  proportion  by  volume  ? 

3.  Why  are  natural  waters  not  chemically  pure?     What  im- 
purities are  there  in  rain  water  ?     In  well  water  ? 

4.  Draw  a  diagram  of  an  apparatus  for  making  distilled  water, 
naming  the  principal  parts  of  the  apparatus. 

5.  Make  a  list  of  the  important  ways  in  which  water  is  found  in 
nature. 

6.  How   may   one   determine  whether    a    substance   contains 
water  ?    Give  a  specific  example. 


THE   COMPOSITION  AND  USES  OF  WATER       21 

7.  About  how  much  water  is  there  in  an  animal  like  a  cat  ? 
In  a  dahlia  root  ? 

8.  What  are  some  of  the  important  characteristics  of  a  good 
drinking  water  ? 

9.  What  is  meant  by  the  term  hard  water  ? 

10.  How  would  you  treat  a  water  that  is  known  to  be  polluted 
and  yet  must  be  used  for  drinking  purposes  ?    Why  ? 


CHAPTER  III 

HYDROGEN,    OXYGEN,    HYDROGEN    PEROXIDE,   AND 

OZONE 

WHILE  both  hydrogen  and  oxygen  are  obtained  when  the 
electric  current  is  passed  through  water,  these  gases  may  also 
be  prepared  by  other  methods.  On  account  of  the  frequent 
occurrence  of  these  elements  in  many  common  substances, 
it  is  necessary  to  study  their  properties  somewhat  more 
closely. 

Hydrogen  is  commonly  prepared  by  the  action  of  an  acid, 
like  hydrochloric  or  sulphuric  acid,  on  certain  metals,  like 
zinc  or  iron,  for  example.  It  is  a  colorless,  odorless,  tasteless 
gas,  which  is  very  light,  in  fact  the  lightest  of  all  known  gases, 
being  14.388  times  lighter  than  air.  One  liter  of  pure  dry 
hydrogen  at  0°  C.  and  under  atmospheric  pressure  at  sea  level 
weighs  0.08987  gram.  Hydrogen  is  an  inflammable  gas. 
When  pure  it  may  be  burned  from  a  jet.  The  flame  is  almost 
colorless,  but  very  hot.  Mixtures  of  air  and  hydrogen,  or 
oxygen  and  hydrogen,  are  explosive,  and  great  care  must  be 
taken  not  to  heat  such  mixtures  or  to  ignite  them  with  a 
flame  or  a  spark.  By  cooling  hydrogen  to  —  253°  C.  it  may  be 
liquified  at  atmospheric  pressure.  Liquid  hydrogen  is  clear 
and  colorless,  that  is,  like  water  in  appearance,  but  it  is 
only  0.07  as  heavy  as  water.  At  —  259°  C.  hydrogen  solid- 
ifies, forming  white  crystals.  Hydrogen  gas  is  not  poisonous, 
but  animals  and  plants  would  die  from  suffocation  when  kept 
in  hydrogen,  because  they  require  oxygen  to  breathe.  Be- 

22 


HYDROGEN,   OXYGEN,   HYDROGEN   PEROXIDE     23 

cause  of  its  lightness  hydrogen  is  used  for  filling  balloons. 
Though  the  gas  burns  with  quite  a  hot  flame,  it  is  not  used 
as  a  fuel  in  the  pure  condition,  for  this  would  be  too  expensive. 
Hydrogen  is,  however,  one  of  the  constituents  of  coal  gas, 
natural  gas,  and  water  gas,  all  of  which  are  used  as  fuels.  When 
hydrogen  burns  in  the  air  or  in  oxygen,  the  product  formed  is 
water.  When  steam  is  passed  over  red-hot  iron,  hydrogen 
is  formed  and  black  oxide  of  iron,  hammer  black,  is  simul- 
taneously obtained,  for  at  the  high  temperature  the  iron 


FIG.  8.  —  Making  hydrogen  by  passing  steam  over  red-hot  iron. 

unites  with  the  oxygen  in  the  water  and  thus  the  hydrogen 
is  set  free.  Magnesium  will  similarly  liberate  hydrogen, 
and  in  this  case  it  suffices  to  immerse  that  metal  in  boiling 
water.  Sodium  will  liberate  hydrogen  from  water  rapidly 
even  at  room  temperature.  Potassium  acts  even  more 
vigorously  than  sodium.  In  the  case  of  sodium  and  po- 
tassium, the  oxides  formed  pass  into  solution  in  the  excess 
of  water  and  form  dilute  lye.  These  solutions  turn  red  litmus 
paper  blue,  are  alkaline  to  the  taste,  and  feel  slippery  to  the 
touch.  Stronger  solutions  of  lye  are  caustic  and  disintegrate 
the  flesh. 


24  CHEMISTRY  AND  DAILY  LIFE 

While  hydrogen  practically  does  not  occur  in  nature  in  the 
free,  i.e.  uncombined,  condition,  it  is  exceedingly  abundant  as  a 
constituent  of  many  compounds.  As  already  mentioned,  one 
ninth  of  the  weight  of  water  is  hydrogen.  All  plant  and 
animal  tissues  contain  hydrogen.  Crude  petroleum  and  all 
of  its  various  products  contain  hydrogen.  This  element  is 
also  found  in  many  rocks. 

Oxygen  occurs  in  the  free  state  in  the  air.  In  fact  it  forms 
about  21  per  cent  of  the  total  volume  of  the  air.  Combined 
with  other  elements,  oxygen  is  also  found  in  large  quantities 
and  very  widely  distributed  over  the  earth.  In  fact  it  is 
the  most  abundant  of  all  of  the  elements,  which  is  readily 
apparent,  for  88.88  per  cent  of  the  weight  of  all  water  is  oxygen, 
and  the  latter  also  forms  44  t°  4$  Per  cent  of  the  weight  of  the 
solid  portions  of  the  earth.  In  all  plants  and  animals  oxygen 
is  combined  with  hydrogen,  carbon,  nitrogen,  phosphorus,  and 
minor  amounts  of  other  elements. 

Pure  oxygen  is  most  readily  prepared  by  heating  certain 
compounds  which  contain  it,  and  which  give  up  their  oxygen 
content  fairly  readily  at  higher  temperatures.  The  substance 
which  is  most  frequently  chosen  for  this  purpose  is  potassium 
chlorate.  It  consists  of  white  crystals  whose  constituents 
are  potassium,  chlorine,  and  oxygen ;  the  latter  element  forms 
39.1  per  cent  of  the  weight  of  this  salt.  Thus  from  100  Ib. 
of  potassium  chlorate  39.1  Ib.  of  oxygen  may  be  obtained. 
The  oxides  of  mercury  and  silver  will  also  decompose  on 
heating,  yielding  free  oxygen,  and  metallic  mercury  and  silver 
respectively.  Again,  saltpeter  when  heated  will  give  up  a 
portion  of  its  oxygen.  Plants  are  continually  giving  off 
oxygen  as  they  breathe. 

Pure  oxygen  is  colorless,  odorless,  and  tasteless.  It  is 
1.1  times  as  heavy  as  air  and  sixteen  times  as  heavy  as 
hydrogen.  A  liter  of  oxygen  at  0°  and  under  a  barometric 


HYDROGEN,   OXYGEN,   HYDROGEN   PEROXIDE     25 

pressure  of  760  mm.  (i.e.  under  the  so-called  standard  con- 
ditions of  temperature  and  pressure  under  which  gases  are 
measured)  weighs  1.429  grams.  Liquid  oxygen  is  pale  blue 
in  color,  boils  at  —  182°. 5  C.,  and  is  1.1315  times  as  heavy 
as  water.  It  is  attracted  by  a  magnet.  By  chilling  liquid 
oxygen  sufficiently,  snow-white  crystals  may  be  obtained, 
which  melt  at  —  227°  C.  In  water  oxygen  is  but  slightly 
soluble,  1  volume  of  water  absorbing  but  0.034  volume  of 
oxygen  at  15°  C.  This  slight  solubility  of  oxygen  in  water 
enables  us  to  collect  the  gas  over  water.  The  fact  that  oxygen 
is  soluble  in  water,  even  if  but  slightly,  is  nevertheless  very  im- 
portant, for  fishes  and  other  organisms  living  in  water  depend 
upon  this  dissolved  oxygen  for  their  supply. 

In  its  ability  to  form  compounds  with  other  elementary 
substances  oxygen  stands  at  the  head  of  the  entire  list  of  the 
chemical  elements.  In  fact,  it  will  unite  with  all  of  the 
elements  except  fluorine  and  the  members  of  the  so-called 
argon  group,  namely  argon,  helium,  neon,  krypton,  and 
xenon.  All  ordinary  combustion  in  the  air  is  really  union  of 
the  burning  substance  with  oxygen.  That  is  to  say,  ordinary 
combustion  is  oxidation.  So  when  coal,  petroleum,  paper,  or 
wood  are  burned  in  the  air  they  are  oxidized.  A  part  of  the 
products  formed  is  gaseous  and  so  escapes  in  the  air,  and 
another  portion  remains  behind  in  the  solid  state  as  ash. 
Now,  when  substances  are  burned  in  pure  oxygen,  the  process 
goes  on  far  more  rapidly  and  more  vigorously.  In  fact,  some 
substances  will  burn  brilliantly  in  pure  oxygen,  whereas  in 
the  air  they  either  would  not  burn  at  all  or  the  action  would 
proceed  very  slowly,  for  it  must  be  borne  in  mind  that  the 
oxygen  in  the  air  is  diluted,  so  to  say,  with  four  times  its  vol- 
ume of  nitrogen,  which  is  a  rather  inert  gas  and  does  not  take 
part  in  ordinary  combustion.  Heated  charcoal  glows  bril- 
liantly in  oxygen.  Sulphur  and  phosphorus  burn  brilliantly 


26 


CHEMISTRY  AND  DAILY  LIFE 


in  oxygen  gas,  and  even  the  steel  of  a  watch  spring  burns  with 
brilliant  scintillations  in  that  gas.  One  can  breathe  pure 
oxygen  for  a  time  without  bad  effects ;  in  fact,  the  gas  is  fre- 
quently administered  to 
patients  who  experience 
difficulty  in  breathing 
and  so  get  an  insuffi- 
cient oxygen  supply  when 
breathing  air.  It  is  in- 
advisable, however,  for  a 
normal  person  to  breathe 
oxygen,  for  thus  the  sys- 
tem gets  too  great  a  sup- 
ply of  that  substance  and 
the  oxidation  processes 
in  the  system  go  on  too 
rapidly. 

The  oxides  of  carbon, 
phosphorus,  sulphur,  and 
certain  other  elements 
readily  dissolve  in  water 
and  form  solutions  that 
are  sour  to  the  taste  and 
turn  blue  litmus  red. 
Such  solutions  are  called  acid  solutions.  It  was  at  one  time 
thought  that  all  acids  contain  oxygen ;  this  is,  however,  not 
the  case,  though  it  is  true  that  by  far  the  larger  number  of 
all  known  acids  do  contain  oxygen.  The  word  oxygen  means 
acid  generator.  It  has  been  retained,  even  though  all  acids 
do  not  contain  oxygen.  The  fact  is  that  all  acids  do  con- 
tain hydrogen,  which  will  be  considered  later. 

Some  oxides,  for  example,  the  oxides  of  sodium,  potassium, 
and  calcium  (obtained  by  burning  each  of  these  metals  in 


FIG.  9.  —  Burning  phosphorus  in  oxygen. 


HYDROGEN,   OXYGEN,  HYDROGEN   PEROXIDE     27 

oxygen)  are  white  powders  which  dissolve  in  water  and  yield 
solutions  that  are  alkaline  to  the  taste,  slippery  to  the  touch, 
and  turn  red  litmus  blue.  Such  solutions  are  called  alkaline 
solutions.  When  acid  solutions  and  alkaline  solutions  are 
mixed,  they  mutually  neutralize  each  other.  The  product 
thus  formed  is  a  salt,  which,  remaining  in  solution,  has  neither 
an  acid  nor  an  alkaline  taste,  and  does  not  affect  either  red 
or  blue  litmus  (see  acids,  alkalies,  salts).  It  thus  appears 
that  by  union  with  some  elements  acidic  oxides  or  acid-form- 
ing oxides  result,  and  by  union  with  other  elements  alkaline 
oxides  or  alkali-forming  oxides  are  obtained.  It  is  true  also 
that  in  some  cases  oxides  are  formed  which  are  neither  acid 
nor  alkali  forming,  but  rather  indifferent  or  neutral  bodies, 
like  the  oxides  of  iron,  copper,  and  mercury,  for  example. 

Ozone  may  be  prepared  from  oxygen.  Three  volumes  of 
oxygen  yield  two  volumes  of  ozone.  On  heating  the  latter 
ordinary  oxygen  is  formed  again,  three  volumes  being 
obtained  from  two  volumes  of  ozone.  Ozone  is  then  1.5 
times  as  heavy,  as  oxygen.  Ozone  is  produced  when  pure 
oxygen  or  the  air  is  subjected  to  the  action  of  electric  sparks. 
So,  for  instance,  in  the  neighborhood  of  a  frictional  electrical 
machine  in  action  there  is  always  a  certain  amount  of  ozone 
produced,  readily  distinguished  by  its  peculiar  garlic-like 
odor.  This  odor  of  ozone  is  also  observed  when  lightning 
strikes  terrestrial  objects  or  when  phosphorus  slowly  oxidizes 
at  room  temperatures  in  moist  air.  Ozone  is  the  most  powerful 
oxidizing  agent  known  and  this  is  its  most  important  property. 
Ozone  will  not  only  kill  germs  and  other  microscopic  organ- 
isms rapidly,  but  it  will  also  oxidize  dyestuffs,  destroying 
their  color,  and  convert  silver,  lead,  arsenic,  sulphur,  and 
other  elements  into  oxides.  On  account  of  its  great  activity, 
ozone  exists  in  the  air  for  but  a  short  time  after  it  has  been 
formed.  Ozone  acts  on  water,  forming  hydrogen  peroxide, 


28  CHEMISTRY  AND  DAILY  LIFE 

also  called  hydrogen  dioxide.  This  is  a  compound  of  oxygen 
and  hydrogen  which  contains  just  twice  as  much  oxygen  as 
does  water.  Thus  in  water  1  gram  hydrogen  is  united  to 
8  grams  of  oxygen,  while  in  hydrogen  peroxide  1  gram  of 
hydrogen  is  united  to  16  grams  of  oxygen.  In  the  pure  state 
hydrogen  peroxide  is  a  thick  sirupy  liquid  whose  specific 
gravity  is  1.458.  It  is  colorless,  but  like  water  it  looks  blue 
in  thick  layers.  This  liquid  is  quite  unstable  and  decomposes 
readily  into  water  and  oxygen.  In  dilute  solutions  it  is  more 
stable,  especially  when  kept  cool  and  in  the  dark.  It  is  now 
a  common  article  of  commerce,  the  3  per  cent  solutions 
frequently  being  sold  under  the  trade  name  of  "  dioxygen." 
This  solution  is  valuable  as  a  mild  bleaching  agent  and 
as  an  antiseptic.  Its  power  as  a  germicide  depends  upon 
the  fact  that  it  readily  decomposes  into  oxygen  and  water. 
The  oxygen  set  free  destroys  the  organisms.  Hydrogen 
peroxide  is  commonly  prepared  by  the  action  of  cold  dilute 
sulphuric  acid  upon  barium  peroxide,  thus : 

Barium  peroxide  plus  sulphuric  acid  yields 

hydrogen  peroxide  plus  barium  sulphate. 

The  latter  substance  may  be  filtered  off.  The  clear  filtrate 
contains  the  hydrogen  peroxide  in  solution.  On  account 
of  the  fact  that  hydrogen  peroxide  also  results  when  water  is 
acted  upon  by  ozone,  the  latter  cannot  exist  long  in  the  air, 
which  always  contains  moisture,  and  this  would  interact 
with  ozone,  forming  hydrogen  peroxide  and  oxygen. 

QUESTIONS 

1.  What  are  the  important  properties  of  hydrogen  ? 

2.  How  may  hydrogen  be  prepared  ? 

3.  In  what  compounds  is  hydrogen  found  in  nature  ? 

4.  What  is  formed  when  hydrogen  burns?     How  may  this  be 
shown  ? 


HYDROGEN,   OXYGEN,   HYDROGEN   PEROXIDE     29 

5.  How  does  oxygen  occur  in  nature  ? 

6.  How  may  pure  oxygen  be  made  ? 

7.  How  many  pounds  of  oxygen  could  be  prepared  from  83 
pounds  of  potassium  chlorate  ? 

8.  Mention  the  important  properties  of  oxygen. 

9.  What  is  an  oxide  ?     How  may  oxides  of  phosphorus,  carbon, 
sulphur,  and  iron  be  formed  ? 

10.  How  may  ozone  be  formed  ?    Mention  its  important  proper- 
ties.    What  is  ozone  ? 

11.  What  is  hydrogen  peroxide  ?    How  may  it  be  prepared  ? 

12.  Mention  the  uses  of  hydrogen  peroxide. 


CHAPTER  IV 
THE   AIR,  NITROGEN,  NITRIC    ACID,  AND   AMMONIA 

THE  main  constituents  of  the  air  are  nitrogen  and  oxygen. 
These  are  present  in  about  the  proportions  of  78  volumes  of 
the  former  to  21  volumes  of  the  latter.  Besides  these  two 
gases  there  are  present,  however,  water  vapor,  carbon  dioxide, 
and  the  elements  of  the  argon  group,  namely  helium,  neon, 
krypton,  and  xenon.  Table  5  gives  the  composition  of  a 
sample  of  air  as  it  is  found  in  the  country  or  over  the  sea. 

TABLE  5 

COMPOSITION  OF  A  SAMPLE  OF  NORMAL  COUNTRY  AIR 
100  volumes  contain  as  follows  : 

Nitrogen 77.42  volumes 

Oxygen 20.77  volumes 

Argon,  helium,  neon,  krypton,  and  xenon      .     .         0.93  volume 

Water  vapor 0.85  volume 

Carbon  dioxide 0.03  volume 

100.00  volumes 

The  amount  of  moisture  which  air  contains  varies  consider- 
ably  from  time  to  time,  depending  especially  upon  temperature 
and  proximity  to  bodies  of  water.  Minor  quantities  of  sulphur 
dioxide,  hydrogen,  ammonia,  nitric  acid,  particles  of  dust, 
and  various  microbes  are  also  present  in  air.  The  amounts 
of  all  of  these  are  also  quite  variable.  While  the  members 
of  the  argon  group  are  present  in  air  to  the  extent  of  over 
0.9  per  cent  by  volume,  these  gases  are  nevertheless  of  no 
practical  importance  and  hence  will  receive  no  further  con- 

30 


AIR,   NITROGEN,   NITRIC   ACID,  AMMONIA       31 

sideration  here.  The  carbon  dioxide  in  the  air  in  the  country 
or  over  the  sea  amounts  to  about  0.03  per  cent  by  volume,  but 
in  cities  where  much  fuel  is  consumed  the  air  often  contains 
double  that  amount  and  even  more,  while  in  densely  crowded 
audience  rooms  the  carbon  dioxide  content  may  run  as  high 
as  six  to  eight  times  that  found  in  city  air.  While  the  carbon 
dioxide  in  the  air  is  present  to  the  extent  of  only  about  0.03 
per  cent,  yet  it  must  be  borne  in  mind  that  plants  get  all  of  their 
carbon  from  the  carbon  dioxide  in  the  atmosphere.  They 
breathe  in  carbon  dioxide,  which  in  the  presence  of  sunlight 
in  the  green  leaf  of  the  plant  interacts  with  the  moisture 
that  is  present,  forming  starch  and  setting  oxygen  free,  which 
the  plant  therefore  exhales.  This  change  may  be  written 
as  follows : 

Carbon  dioxide  +  water  (in  the  sunlight  in  the 

green  leaf  of  the  plant)  yields  starch  +  oxygen. 

The  constituents  of  the  air,  Table  5,  are  not  chemically 
united;  they  form  merely  a  mixture.  In  spite  of  this  the 
relative  amounts  of  oxygen,  nitrogen,  and  argon  are  nearly 
constant  in  the  atmosphere  everywhere. 

The  highest  amounts  of  moisture  which  the  air  is  able  to 
hold  at  different  temperatures  is  shown  in  Table  6. 

TABLE  6 

TEMPERATURE  OF  AMOUNT  OF  WATER  VAPOR  IN 

SATURATION  1  Cu.  METER  OF  SATURATED  AIR 

-5°  C 4.0  grams 

0°C 5.4  grams 

+5°  C ;  .  .  7.3  grams 

10°  C 9.7  grams 

15°  C 13.0  grams 

20°  C 17.1  grams 

22°  C 22.5  grams 

30°  C. 30.0  grams 


32  CHEMISTRY  AND   DAILY  LIFE 

If  the  air  has  but  0.4  of  the  water  vapor  in  it  that  it  can 
hold,  we  feel  that  the  air  is  dry.  If,  however,  0.8  of  its 
maximum  capacity  of  moisture  is  present  in  the  air,  we 
feel  that  it  is  moist  or  humid.  As  the  moist  air  reaches  the 
upper  and  cooler  regions  of  the  atmosphere,  partial  con- 
densation of  the  water  to  minute  drops  takes  place,  form- 
ing mists,  which  on  account  of  their  altitude  are  commonly 
called  clouds.  When  the  mists  form  near  the  surface  of  the 
earth,  they  are  called  fogs.  These  are  formed  when  mois- 
ture-laden air  is  cooled  to  such  an  extent  that  a  portion  of  its 
moisture  is  condensed.  This  is  frequently  caused  by  a  cold 
current  of  air  striking  warmer  moisture-laden  strata.  When 
the  condensation  in  the  upper  regions  of  the  air  is  such  that 
large  drops  are  formed,  these  fall  to  the  ground  as  rain,  and 
carry  with  them  in  solution  some  of  all  of  the  gases  in  the 
atmosphere,  together  with  fine  particles  of  dust,  microor- 
ganisms, etc.,  that  were  suspended  in  the  air.  This  material 
on  reaching  the  ground  soaks  into  the  soil  in  part,  and  in 
part  it  flows  off  the  surface  into  brooks,  rivers,  lakes,  and 
the  sea.  It  has  been  estimated  that  about  80  per  cent  of 
the  water  that  falls  as  rain  on  the  land  soaks  into  the  ground 
and  20  per  cent  runs  off  the  surface  into  the  waterways. 
Snow,  sleet,  and  hail  form  at  temperatures  at  and  below  the 
freezing  point  of  water.  Dew  forms  at  night.  It  consists 
of  drops  of  moisture  that  deposit  upon  objects  which  cool 
off  relatively  rapidly,  and  so  chill  the  moisture-laden  air 
that  comes  into  contact  with  them.  The  importance  of 
these  various  aqueous  precipitations  for  the  life  of  plants 
will  receive  further  consideration  later. 

The  common  way  of  preparing  nitrogen  gas  is  to  abstract 
the  oxygen  from  an  inclosed  space  of  air.  This  may  be  done 
in  various  ways.  So,  for  example,  an  animal  like  a  rat  or  a 


AIR,   NITROGEN,   NITRIC.  ACID,   AMMONIA       33 


mouse  may  be  placed  in  a  tightly  stoppered  bottle,  where- 
upon it  will  soon  suffocate,  because  it  will  use  up  the  oxygen 
in  the  air  in  the  bottle  and  breathe  out  carbon  dioxide.  The 
latter  gas  may  be  removed  by  shaking  the  gas  left  in  the 
bottle  with  some  clear  limewater.  The  limewater  be- 
comes milky  in  appearance  because  a  precipitate  of  car- 
bonate of  lime,  calcium  carbonate,  is  formed,  thus : 

Limewater  -f-  carbon  dioxide  yields 

calcium  carbonate  +  water. 

By  this  chemical  change,  then,  the  carbon  dioxide  is  removed, 

being  made  part  and  parcel  of  a  solid  substance,  the  calcium 

carbonate,  which  is  chemically  the  same  as  chalk.     Now  the 

gas  which  still  remains  in  the  bottle  is  nitrogen  plus  the 

gases  of  the  argon  group.     These  latter  in  all  make  up 

only  about  0.9  per  cent  of  the  entire  air.     They  have  all 

been  discovered  in  the  air  since  1895.     They  are  very  inert, 

in  fact  thus  far  it  has  been  found  to  be  impossible  to  get  them 

to  unite  chemically  with  any  other  element.     By  simply 

removing  the  oxygen  and  carbon  dioxide  from  the  air,  pure 

nitrogen  is  not   obtained,  for   the 

gases  of  the  argon  group  are  still 

present.    For  the  present  purposes, 

however,  it  will  not  be  necessary 

to  devote  space  to  the  description 

of  how  the  latter  gases  may  be 

removed;   suffice  it  here  to   say 

that    perfectly   pure    nitrogen    is 

best  prepared  from  certain  pure 

chemical  compounds  in  which  it 

occurs.     The    oxygen   of   the  air 

may  also  be  removed  by  burning  certain  substances  in  the 

air  in  a  closed  space.     So  one  may  burn  a  bit  of  sponge 


FIG.  10.  —  Removing  oxygen 
from  the  air  by  burning 
alcohol  in  it. 


34  CHEMISTRY  AND  DAILY  LIFE 

saturated  with  alcohol  in  a  bottle  inverted  in  a  dish  of 
water  as  shown  in  Fig.  10.  In  this  case  water  and  carbon 
dioxide  are  formed  and  the  latter  gas  is  absorbed  by  the 
water  in  the  bottle.  In  place  of  the  alcohol  a  bit  of  phos- 
phorus may  be  burned  similarly  in  the  bottle.  In  this  case 
the  phosphorus  unites  with  the  oxygen,  forming  phosphoric 
oxide,  which  dissolves  in  the  water,  thus  leaving  the  nitro- 
gen intact.  In  both  of  the  last  experiments  the  water 
rises  on  the  inside  of  the  bottle,  filling  the  latter  to  the 
extent  of  one  fifth  of  the  original  volume  occupied  by  the 
air,  thus  showing  that  four  fifths  of  the  air  is  nitrogen  and  one 
fifth  oxygen. 

If  a  burning  splinter  or  a  lighted  candle  is  thrust  into 
nitrogen  gas,  the  flame  is  at  once  extinguished,  showing  that 
nitrogen  will  not  support  combustion.  Animals  suffocate  in 
nitrogen,  and  die  for  lack  of  oxygen.  Nitrogen  gas  is  not 
poisonous,  but  it  cannot  be  used  in  respiration.  In  the  air 
it  dilutes  the  oxygen  that  is  present  and  so  retards  the  too 
rapid  oxidation  that  would  take  place  if  pure  oxygen  were 
inhaled.  At  ordinary  temperatures  nitrogen  is  quite  an  inert 
gas,  but  at  high  temperatures  it  does  combine  with  other  sub- 
stances chemically.  So,  for  example,  nitrogen  does  not  unite 
with  oxygen  when  these  gases  are  mixed.  In  fact  no  union 
takes  place,  even  if  these  gases  are  heated  together  quite 
highly,  as,  for  instance,  when  the  mixture  is  passed  through 
a  red-hot  tube.  But  if  a  mixture  of  nitrogen  and  oxygen  is 
subjected  to  the  very  high  temperature  of  the  electric  arc, 
union  does  take  place,  oxide  of  nitrogen  being  thus  formed. 
The  latter  when  treated  with  air  and  water  yields  nitric 
acid,  and  indeed  this  process  is  now  used  successfully  in  form- 
ing that  important  substance  on  a  commercial  scale.  As 
electricity  is  required  in  the  process,  this  method  of  manu- 
facturing nitric  acid  is  only  profitable  where  water  power  is 


AIR,   NITROGEN,   NITRIC   ACID,   AMMONIA       35 

available  for  the  production  of  cheap  electric  energy.  In 
Norway  considerable  quantities  of  nitric  acid  and  nitrates, 
which  are  important  as  fertilizers,  are  thus  manufactured  at 
present.  As  the  lightning  flashes  through  air  during  thunder- 
storms, nitric  acid  and  nitrates  are  similarly  produced,  and 
these  as  they  are  carried  down  by  the  rain  enrich  the  soil. 
It  is  for  this  reason  that  a  thundershower  is  much  more  helpful 
to  vegetation  than  merely  an  ordinary  rain.  The  latter  supplies 
water,  but  the  former  furnishes  fertilizer  as  well  as  water. 

The  two  most  important  common  compounds  of  nitrogen  are 
nitric  acid  and  ammonia.     How  nitric  acid  may  be  made 


FIG.  11.  —  Making  nitric  acid. 

from  the  air  and  water  has  just  been  stated.  It  may  also 
be  made  from  saltpeter,  i.e.  potassium  nitrate,  by  treatment 
with  strong  sulphuric  acid  and  heating.  Thus  the  nitric 
acid  is  liberated  and  distills  over  into  the  receiver  as  shown 
in  Fig.  11.  Instead  of  the  somewhat  costly  potassium  ni- 


36  CHEMISTRY  AND  DAILY  LIFE 

trate,  sodium  nitrate,  which  is  mined  in  Chili  and  conse- 
quently called  Chili  saltpeter,  may  be  used.  Thus  nitric 
acid  and  sodium  sulphate  are  produced,  instead  of  nitric 
acid  and  potassium  sulphate.  We  may  write  these  changes 
thus : 

Potassium  nitrate  4-  sulphuric  acid  = 

nitric  acid  4-  potassium  sulphate. 

Sodium  nitrate  +  sulphuric  acid  = 

nitric  acid  +  sodium  sulphate. 

Pure  nitric  acid  is  a  colorless  liquid  having  a  pungent  odor. 
Its  specific  gravity  is  1.414  at  15°  C.  In  the  sunlight  the 
liquid  turns  yellowish  in  color,  due  to  partial  decomposition. 
Nitric  acid  is  a  wry  powerful  acid  and  also  a  strong  oxidizing 
agent.  It  turns  blue  litmus  red,  discolors  indigo  solution, 
disintegrates  cloth,  corrodes  the  flesh,  and  turns  the  skin 
yellow.  Metals,  with  the  exception  of  gold  and  platinum, 
are  acted  upon  by  nitric  acid,  being  converted  either  into 
nitrates  or  oxides.  The  various  salts  of  nitric  acid  are  all 
called  nitrates.  The  nitrates,  especially  those  of  potassium, 
ammonium,  calcium,  and  sodium,  are  very  important  as 
fertilizers.  While  nitric  acid  does  not  occur  in  nature  as 
such,  its  salts,  that  is,  the  nitrates,  are  quite  widely  distributed 
in  the  soil.  In  the  air  nitrate  of  ammonium  is  also  present. 
Nitrates  are  exceedingly  important  as  soil  constituents,  for  it 
is  from  them  that  plants  get  their  supply  of  nitrogen.  The 
nitrates  in  the  soil  are  contained  in  the  soil  water  which 
holds  them  in  solution. 

Nitric  acid  is  also  used  in  manufacturing  sulphuric  acid, 
in  which  case  it  serves  to  oxidize  sulphur  to  its  highest  stage 
of  oxidation.  Furthermore,  in  making  collodion,  gun  cotton, 
dynamite,  and  smokeless  powder,  nitric  acid  is  used  in  large 
quantities. 


AIR,   NITROGEN,   NITRIC   ACID,   AMMONIA        37 

Nitrous  acid  may  be  obtained  from  nitric  acid  by  robbing 
the  latter  of  a  part  of  its  oxygen.  The  salts  of  nitrous  acid 
are  called  nitrites ;  they  occur  in  the  soil,  as  a  result  of  the 
decomposition  of  plant  and  animal  matter.  All  plants 
and  animals  contain  nitrogen  in  combination  with  carbon, 
hydrogen,  oxygen,  and  minor  amounts  of  sulphur  and  phos- 
phorus. When  the  plant  and  animal  tissues  decay,  nitrogen 
is  set  free  in  part,  and  in  part  it  is  converted  into  ammonia, 
a  compound  of  nitrogen  and  hydrogen,  and  the  ammonia 
is  gradually  oxidized  to  nitrites  and  finally  to  nitrates. 
The  latter  represent  the  highest  oxidation  products.  While 
the  nitrates  in  the  soil  are  a  very  important  source  from  which 
plants  derive  their  supply  of  nitrogen,  they  are  by  no  means  the 
only  source. 

Ammonia  is  a  compound  of  nitrogen  and  hydrogen.  It 
contains  14  parts  of  the  former  to  3  parts  of  the  latter  by 
weight.  By  volume  the  composition  is  represented  by  the 
following  equation : 

3  volumes  of  hydrogen  4-  1  volume  of  nitrogen  = 

2  volumes  of  ammonia. 

Hydrogen  and  nitrogen  do  not  combine  at  all  readily,  how- 
ever, even  when  the  gases  are  heated  together  highly,  as,  for 
instance,  by  means  of  the  electric  spark.  On  thus  subject- 
ing a  mixture  of  hydrogen  and  nitrogen  gases  to  the  contin- 
uous action  of  the  electric  spark,  a  small  fraction  of  a  per 
cent  of  the  gases  present  is  converted  to  ammonia.  But  by 
heating  nitrogenous  plant  or  animal  tissues,  with  little  or  no 
access  of  air,  ammonia  is  readily  obtained,  especially  when 
the  organic  matter  used  is  mixed  with  lime  or  caustic  soda  or 
potash  and  then  subjected  to  heat.  In  fact  the  ammonia 
and  all  of  the  ammonium  compounds  of  commerce  are  obtained 
as  a  by-product  of  the  manufacture  of  illuminating  gas  from 


38  CHEMISTRY  AND   DAILY  LIFE 

coal.  In  the  latter  process  the  coal,  which  represents  the 
remains  of  the  vegetation  of  the  carboniferous  age  and 
other  early  geological  periods,  is  heated  out  of  contact  of  the 
air.  The  gases  that  escape  are  washed  by  gurgling  them 
through  water,  and  the  ammonia  is  then  found  dissolved  in 
this  water.  Plant  and  animal  matter,  including  coal,  peat, 
etc.,  all  contain  nitrogen  and  hydrogen  in  combination  with 
carbon,  oxygen,  sulphur,  phosphorus,  etc.,  and  when  this 
material  is  heated  out  of  contact  with  the  air  (i.e.  subjected 
to  dry  distillation,  also  called  destructive  distillation),  a 
variety  of  gaseous  products  are  formed,  among  which  is 
ammonia.  The  latter  forms  by  union  of  nitrogen  and  hydro- 
gen from  the  organic  matter. 

Ammonia  gas  is  colorless  and  only  0.59  as  heavy  as  air. 
It  has  a  very  characteristic,  sharp,  penetrating  odor,  irri- 
tates the  mucous  membranes,  and  causes  a  flow  of  tears. 
One  cannot  inhale  the  gas.  Animals  soon  die  in  it.  The 
gas  does  not  support  combustion  and  does  not  burn  in  the 
air ;  but  it  may  be  burned  in  oxygen.  About  700  volumes 
of  ammonia  gas  will  dissolve  in  1  volume  of  water  at  ordi- 
nary temperatures.  This  solution  is  lighter  than  water. 
At  14°  C.  the  saturated  solution  has  a  specific  gravity  of 
0.8844  and  contains  36  per  cent  of  ammonia  by  weight. 
The  solution  of  ammonia  gas  in  water  is  popularly  called 
ammonia  water,  spirits  of  hartshorn,  and  aqua  ammonia. 
It  has  the  same  odor  as  ammonia  gas,  for  the  latter  is  con- 
tinually being  given  off  by  the  solution.  Indeed,  all  of  the 
ammonia  gas  may  be  expelled  from  the  solution  by  boiling 
the  same.  Finally  water  alone  remains  behind.  Ammonia 
turns  red  litmus  blue,  and  is  consequently  alkaline,  which 
is  further  evidenced  by  the  fact  that  it  will  unite  directly 
with  acids,  neutralizing  them  and  forming  ammonium  salts. 
So  with  nitric  acid  ammonia  forms  ammonium  nitrate,  with 


AIR,   NITROGEN,   NITRIC  ACID,   AMMONIA       39 

sulphuric  acid  ammonium  sulphate,  with  hydrochloric  acid 
ammonium  chloride.  All  ammonium  salts  may  be  volatilized 
by  heating  them.  On  treating  any  ammonium  salt  with  lime 
or  lye,  ammonia  gas  is  evolved,  and  this  is  the  best  way  to 
prepare  pure  ammonia  gas.  For  example : 

Ammonium  chloride  H-  soda  lye  = 

sodium  chloride  +  ammonia  +  water. 

(common  salt) 

Ammonia  water  is  used  in  the  household  in  cleansing  clothes 
and  polishing  metals.  It  does  not  attack  the  latter  as 
drastically  as  acids  do,  and  consequently  is  less  objectionable. 
Ammonia  is  formed  wherever  nitrogenous  plant  and  animal 
remains  are  decaying.  So,  for  instance,  it  is  found  in  stables, 
in  dung  piles,  in  the  leachings  from  the  latter,  and  in  the 
soil.  When  thus  formed  from  rotting  organic  matter, 
ammonia  at  once  combines  with  any  acids  that  may  be 
present,  especially  with  carbonic  acid  gas,  which  is  always 
at  hand,  being  a  constituent  of  the  air.  In  the  soil,  then, 
ammonia  is  present  in  the  form  of  ammonium  salts,  among 
these  ammonium  nitrate,  ammonium  nitrite,  ammonium  car- 
bonate, ammonium  chloride,  and  ammonium  sulphate  are  the 
most  important.  All  of  the  ammonium  salts  are  soluble  in 
water,  and  hence  are  present  in  solution  in  the  soil  water. 
From  ammonium  salts  thus  dissolved  in  the  waters  of  the  soil, 
plants  derive  a  considerable  share  of  their  supply  of  nitrogen, 
hence  the  value  of  ammonium  salts  as  fertilizers.  In  com- 
merce ammonium  sulphate,  which  contains  21  per  cent  nitro- 
gen, is  quite  generally  sold  as  a  fertilizer.  It  is  manufac- 
tured at  the  gas  works  in  large  cities  as  a  by-product  in 
making  coal  gas. 


40  CHEMISTRY  AND   DAILY  LIFE 

QUESTIONS 

1.  (a)  What  are  the  constituents  of  the  air  ? 

(b)  In  what  proportions  do  the  two  main  constituents  occur 
in  the  air  ? 

2.  Of  what  use  is  the  carbon  dioxide  in  the  air  ? 

3.  When  does  the  air  feel  dry  ?     When  moist  ? 

4.  What  becomes  of  the  water  that  falls  to  the  ground  as  rain  ? 
6.  What  is  dew  ?    Snow  ?    Sleet  ?    Hail  ? 

6.  How  may  nitrogen  be  prepared  ?    Give  its  principal  proper- 
ties. 

7.  Why  will  an  animal  die  in  nitrogen  gas  ? 

8.  How  may  nitric  acid  be  formed  ? 

9.  What  are  the  properties  of  nitric  acid  ? 

10.  Of  what  use  are  nitrates  in  the  soil  ? 

11.  What  is  ammonia  ?    How  prepare  it  ? 

12.  What  is  ammonia  water  ?    What  is  it  used  for  ? 

13.  Why  are  ammonium  salts  useful  as  fertilizers  ?    From  what 
source  are  these  salts  obtained  ? 

14.  Mention  the  important  forms  in  which  nitrogen  occurs  in 
nature. 


CHAPTER  V 
ACIDS,  ALKALIES,  SALTS,  AND  CHEMICAL  FORMULAS 

WE  have  already  learned  that  when  carbon,  sulphur,  or 
phosphorus  are  burned  and  the  products  of  combustion  are 
dissolved  in  water,  liquids  are  obtained  which  have  a  sour 
taste  and  redden  blue  litmus.  Substances  possessing  such 
characteristics  are  commonly  termed  acids.  Acids  occur 
in  nature  in  plants,  in  animals,  and  also  in  the  mineral  world. 
So,  for  example,  the  sourness  of  the  lemon  is  due  to  the 
citric  acid  which  it  contains.  The  latter  substance  may  be 
prepared  from  lemon  juice.  It  consists  of  beautiful  color- 
less crystals  which  are  readily  soluble  in  water.  The  solu- 
tion has  a  markedly  sour  taste.  This  same  citric  acid  is 
found  in  other  citrous  fruits  as  well,  and  is  most  abundant 
in  them  before  they  are  quite  ripe.  In  sour  apples,  moun- 
tain ash  berries,  and  many  other  similar  fruits  malic  acid 
is  present.  It  too  may  be  prepared  from  these  in  the  pure 
state.  It  is  a  white  solid  substance  which  is  readily  soluble 
in  water.  Similarly  grapes  contain  tartaric  acid.  The  jack- 
in-the-pulpit  contains  oxalic  acid.  On  fermentation  of 
apple  juice,  vinegar,  which  is  essentially  a  dilute  solution  of 
acetic  acid,  is  formed.  When  milk  sours,  lactic  acid  is  formed, 
and  indeed  lactic  acid  also  occurs  in  the  muscles  of  man  and 
animals.  In  the  human  stomach  hydrochloric  acid  is  formed 
by  the  gastric  glands.  In  red  ants  formic  acid  is  found. 
The  air,  as  we  have  seen,  always  contains  a  small  amount  of 
carbonic  acid,  and  in  cities  where  much  coal  is  consumed,  it 

41 


42  CHEMISTRY  AND   DAILY  LIFE 

also  contains  sulphurous  acid,  for  coal  contains  sulphur.. 
All  natural  waters,  too,  contain  carbonic  acid  in  solution, 
and  some  spring  waters  are  highly  charged  with  this  sub- 
stance. Soil  waters  also  contain  acids  formed  during  the 
processes  of  decay  of  animal  and  vegetable  matter.  Boric 
acid  is  found  in  volcanic  regions  to  some  extent,  and  silicic 
acid  is  one  of  the  most  abundant  of  all  substances.  It 
occurs  as  quartz  in  huge  masses,  often  forming  mountains, 
and  as  sand  grains  it  covers  vast  areas  of  the  earth's  surface. 
Silicic  acid  is  practically  insoluble  in  water.  It  conse- 
quently has  no  taste  and  does  not  redden  litmus.  How- 
ever, with  alkalies  it  has  the  power  to  form  salts,  which 
indeed  is  after  all  the  most  important  characteristic  of  all 
acids.  In  fact  some  acids  are  so  weak  that  they  do  not  redden 
litmus,  and  haw  no  perceptible  sour  taste,  and  yet  they  are 
unquestionably  acidic  substances  because  they  do  form  salts 
with  alkalies. 

Lime,  as  it  is  used  for  building  purposes,  soda  lye,  potash 
lye,  and  ammonia  are  substances  which  turn  moist  red  litmus 
paper  blue.  They  are  typical  alkalies.  In  strong  solutions 
they  have  a  caustic  or  corrosive  action  on  .the  skin.  With 
acids  they  react  chemically,  forming  new  substances  called 
salts.  So,  for  example,  when  a  solution  of  soda  lye  is  treated 
with  a  solution  of  hydrochloric  acid  till  the  resulting  liquid 
does  not  change  either  red  or  blue  litmus  paper,  we  say  that 
the  acid  and  the  lye  have  neutralized  each  other.  The  sub- 
stance which  is  now  in  the  solution  is  common  salt.  It  has 
a  salty  taste,  whereas  the  acid  had  a  sour  taste,  and  the  lye 
had  an  alkaline  taste  which  is  quite  peculiar  to  itself.  The 
change  which  takes  place  when  the  acid  and  the  lye  act  on 
each  other  may  be  expressed  in  the  form  of  an  equation  thus  : 

Soda  lye  +  hydrochloric  acid  yields 

sodium  chloride  (i.e.  common  salt)  +  water. 


ACIDS,  ALKALIES,  SALTS,  CHEMICAL  FORMULAS     43 

Now  it  is  somewhat  cumbersome  to  write  such  equations 
in  words,  and  in  order  to  save  space  and  time,  chemists  have 
adopted  a  system  of  abbreviations  which  is  very  easily 
comprehended.  Each  element  is  represented  by  the  initial 
letter  of  its  name.  Thus  C  is  the  symbol  for  carbon,  H  stands 
for  hydrogen,  O  for  oxygen,  N  for  nitrogen,  P  for  phos- 
phorus, I  for  iodine,  etc.  As  several  of  the  elements  have 
names  that  begin  with  the  same  letter,  their  symbols  are 
distinguished  from  one  another  by  adding  to  the  first  letter 
(which  is  always  capitalized)  one  other  characteristic  letter 
contained  in  the  name  of  the  element.  This  second  letter 
is  never  capitalized.  So,  for  example,  C  stands  for  carbon, 
Ca  for  calcium,  Co  for  cobalt,  Cl  for  chlorine,  etc.  While 
in  some  cases  the  symbol  is  derived  from  the  common  name 
of  the  element  (as  already  illustrated),  in  other  instances  it  is 
derived  from  the  Latin  name  of  the  element.  So  sodium, 
natrium,  has  the  symbol  Na ;  potassium,  kalium,  K ;  copper, 
cuprum,  Cu ;  silver,  argentum,  Ag ;  iron,  ferrum,  Fe ;  mer- 
cury, hydrargyrum,  Hg ;  tin,  stannum,  Sn ;  gold,  aurum,  Au ; 
(compare  Table  1).  Now  these  symbols  do  not  stand  for 
the  names  of  the  elements  only,  but  they  also  represent 
definite  quantities  by  weight  in  which  the  elements  combine 
chemically.  So  H  stands  for  hydrogen,  but  also  for  1  gram 
of  hydrogen ;  Cl  stands  for  chlorine,  but  also  for  35.5  grams 
of  chlorine ;  O  represents  oxygen,  but  also  16  grams  of  oxy- 
gen ;  etc.  Table  7  gives  the  names  of  the  more  common 
elements  together  with  their  symbols  and  the  number  of 
parts  by  weight  for  which  each  symbol  stands.  A  complete 
list  of  the  chemical  elements  and  their  symbols  has  already 
been  given  on  page  3.  While  Table  7  mentions  but  thirty- 
eight  of  the  elements,  the  data  are  nevertheless  quite  suffi- 
cient for  all  ordinary  purposes,  for  the  elements  that  have 
been  omitted  are  of  minor  importance. 


44 


CHEMISTRY  AND   DAILY  LIFE 


Al 

27.1 

Lead 

Pb 

207.10 

Sb 

120.2 

Lithium  .     .     . 

.     Li 

6.94 

As 

74.96 

Magnesium  .     . 

.     Mg 

24.32 

Ba 

137.37 

Manganese  .     . 

.     Mn 

54.93 

Bi 

208.0 

Mercury       .     . 

:    Hg 

200.6 

B 

11.0 

Molybdenum    . 

.     Mo 

96.0 

Br 

79.92 

Nickel     .     .     . 

Ni 

58.68 

Cd 

112.40 

Nitrogen      .     . 

.     N 

14.01 

Ca 

40.07 

Oxygen   .     .     . 

.     0 

16.0 

C 

12.0 

Phosphorus 

.     P 

31.04 

Cl 

35.46 

Platinum      .     . 

.     Pt 

195.2 

Cr 

52.0 

Potassium    .     . 

.     K 

39.10 

Co 

58.97 

Silicon     .     .     . 

.     Si 

28.3 

Cu 

63.57 

Silver      .     .     . 

.     Ag 

107.88 

F 

19.0 

Sodium    .     .     . 

.     Na 

23.0 

Au 

197.2 

Strontium    .     . 

.     Sr 

87.62 

H 

1.008 

Sulphur  .     .     . 

.     S 

32.07 

I 

126.92 

Tin     .... 

.     Sn 

119.0 

Fe- 

55.84 

Zinc    . 

Zn 

65.35 

TABLE  7 

Aluminum  . . 
Antimony 

Arsenic       .  . 

Barium      .  . 

Bismuth    .  . 

Boron    .     .  . 

Bromine     .  . 

Cadmium  .  . 

Calcium     .  . 

Carbon       .  . 

Chlorine     .  . 
Chromium 

Cobalt  .     .  . 

Copper  .     .  . 

Fluorine     .  . 

Gold      .     .  . 

Hydrogen  .  . 

Iodine   .     .  . 

Iron       .     .  . 

The  figures  in  Table  7  have  all  been  determined  by 
ascertaining  the  weights  of  the  elements  that  unite  to  form 
compounds.  Experience  has  shown  that  chemical  compounds 
when  pure  always  contain  the  same  elements  in  the  same  pro- 
portion by  weight.  This  is  called  the  law  of  definite  propor- 
tions. So,  for  instance,  hydrochloric  acid  always  consists 
of  hydrogen  and  chlorine,  and  nothing  else.  Moreover,  in 
hydrochloric  acid  there  are  35.5  grams  of  chlorine  combined 
with  every  gram  of  hydrogen;  that  is  to  say,  for  every  1 
part  by  weight  of  hydrogen,  hydrochloric  acid  contains 
35.5  parts  by  weight  of  chlorine,  and  this  is  represented  by 
the  symbol  HC1,  commonly  termed  the  formula  for  hydro- 
chloric acid.  Again,  in  common  salt,  which  is  sodium  chlo- 
ride, we  always  have  35.5  parts  by  weight  of  chlorine  com- 
bined with  23  parts  by  weight  of  sodium.  The  symbol  or 
formula  for  common  salt,  .then,  is  NaCl,  and  it  expresses  both 
the  qualitative  and  quantitative  composition  of  sodium  chloride. 


ACIDS,  ALKALIES,  SALTS,  CHEMICAL  FORMULAS    45 

We  may  indeed  regard  common  salt,  i.e.  NaCl,  as  derived 
from  hydrochloric  acid,  i.e.  HC1,  the  1  part  by  weight  of 
hydrogen  of  the  latter  being  replaced  by  23  parts  of  sodium 
by  weight.  Thus  23  parts  of  sodium  by  weight  may  replace 
1  part  of  hydrogen  by  weight,  and  consequently  23  is  said  to 
be  the  hydrogen  equivalent  of  sodium ;  for  it  has  been  found 
to  be  true  in  general  that  whenever  sodium  can  replace  hydrogen 
in  a  compound  it  takes  23  grams  of  sodium  to  play  the  role  of 

1  gram  of  hydrogen.      The  hydrogen   equivalent  of  other 
elements  may  be  found  similarly.     Such  replacements  are 
very  easily  represented  by  means  of  the  chemical  symbols 
mentioned.     Thus : 

HC1  +  Na 

(36.5  grams  hydrochloric  acid)  +  (23  grams  sodium)  yield 

NaCl  +          H 

(58.5  grams  common  salt)  +  (1  gram  hydrogen) 

In  general,  then,  the  composition  of  any  compound  is  expressed 
by  writing  the  symbols  of  its  elements  one  after  the  other.  How- 
ever, whenever  the  compound  is  a  gas  or  vapor,  the  symbols 
that  represent  it  indicate^  not  only  the  qualitative  composi- 
tion and  quantitative  composition  by  weight,  but  also  the 
weight  of  22.4  liters  of  the  gas  or  vapor  at  0°  C.  and  760  mm. 
barometric  pressure.  So,  for  example,  the  symbol  HC1 
stands  for  hydrochloric  acid  and  indicates  that  in  this  com- 
pound 1  gram  of  hydrogen  is  combined  with  35.5  grams 
chlorine ;  it  shows  also,  however,  that  22.4  liters  of  the  gas 

or»    r 

weigh  36.5  grams,  whence  1  liter  weighs  ^rr> or  1-629  grams. 

22.4: 

The  volume  22.4  liters  is  chosen  because  it  is  the  volume  of 

2  grams  of  hydrogen  at  0°  C.  and  760  mm.  pressure,  with 
which  it  is  customary  to  compare  other  gases.     It  is  not 
necessary  to  enter  further  into  the  reasons  for  this  practice 
here.     For  our  purpose  it  suffices  to  know  that  in  the  case 


46  CHEMISTRY  AND  DAILY  LIFE 

of  any  gas  the  weight  of  a  liter  of  it  may  be  found  by  dividing 
the  formula  weight  by  224-  The  following  examples  will 
serve  as  illustrations.  The  composition  of  carbon  dioxide 
gas  is  represented  by  CO2,  which  indicates  that  12  grams  of 
carbon  are  combined  with  2X16  or  32  grams  of  oxygen ; 
furthermore,  the  formula  indicates  that  12  +  32  or  44  grams 
(the  formula  weight)  is  the  weight  of  22.4  liters  of  the  gas, 

44 

whence  1  liter  weighs  rr-r,  or  1.964  grams.     Again,  the  for- 
££A 

mula  for  water  is  H2O,  which  shows  that  it  consists  of  hydro- 
gen and  oxygen  in  the  ratio  of  2  grams  of  the  former  to 
16  grams  of  the  latter;  it  also  indicates,  however,  that 
2  +  16  or  18  grams  of  water  vapor  occupy  22.4  liters  of 
space  under  standard  conditions,  whence  1  liter  of  the  vapor 

I  O 

weighs  on~i>  or  0.8035  gram.      From  the  above  illustrations 

the  use  of  subscripts  to  the  symbols  of  the  elements  is  per- 
haps already  sufficiently  evident,  but  two  further  illustra- 
tions will  here  be  given.  The  symbol  for  cane  sugar  is 
C^H^Oii,  which  shows  that  this  compound  is  composed  of 
12  X  12  or  144  parts  of  carbon  by  weight,  to  every  1  X  22 
or  22  parts  of  hydrogen  by  weight,  to  every  11  X  16  or  176 
parts  of  oxygen  by  weight ;  in  other  words  every  342  grams 
of  sugar  contain  144  grams  of  carbon  plus  22  grams  of  hydro- 
gen plus  176  grams  of  oxygen.  The  symbol  for  phosphoric 
acid  anhydride,  also  called  phosphorus  pentoxide,  is  P2O5. 
This  formula  shows  that  this  compound  is  composed  of  phos- 
phorus and  oxygen  in  the  proportions  of  2  X  31  or  62  grams 
of  the  former  to  5  X  16  or  80  grams  of  the  latter. 

The  use  of  chemical  symbols,  then,  serves  to  express  quite  a 
number  of  facts  about  a  chemical  compound  in  compact  form. 
A  few  of  'the  chemical  changes  already  studied  will  now 
be  expressed,  using  chemical  symbols  and  equations. 


ACIDS,  ALKALIES,  SALTS,  CHEMICAL  FORMULAS     47 

These  will  serve  to  illustrate  further  how  the  formulas  are 
used. 

(1)  When  iron  filings  and  sulphur  are  heated   together, 
ferrous  sulphide  is  formed.     Thus  : 

Fe      +      S      =  FeS 

iron  sulphur  ferrous  sulphide 

56  grams        32  grams  88  grams 

(2)  When  carbon  is  burned  in  oxygen  or  in  the  air,  car- 
bon dioxide  is  formed.     Thus  : 

C      +       02      =        CO2 

carbon  oxygen          carbon  dioxide 

12  grams       32  grams  44  grams 

(3)  When  phosphorus  is  burned  in  oxygen,  phosphorus 
pentoxide  is  formed.     Thus  : 

P2       +      05      =  P206 

phosphorus          oxygen          phosphorus  pentoxide 
62  grams         80  grams  142  grams 

(4)  When  sulphuric  acid  acts  on  zinc,  hydrogen  and  zinc 
sulphate  are  formed.     Thus  : 

H2SO4      +     Zn       =     H2     +       ZnS04 

sulphuric  acid  zinc  hydrogen         zinc  sulphate 

98  grams  65  grams          2  grams  161  grams 

(5)  When   hydrochloric   acid   is   neutralized   by   sodium 
hydroxide,  sodium  chloride  and  water  are  formed.     Thus  : 

HC1        +        NaOH      =       NaCl       +    H2O 

hydrochloric  acid      sodium  hydroxide       sodium  chloride          water 
36.5  grams  40  grams  58.5  grams  18  grams 

(6)  When  potassium  chlorate  is  heated,  it  yields  oxygen 
and  potassium  chloride.     Thus  : 

KC1O3  3O     +  KC1 

potassium  chlorate  oxygen  potassium  chloride 

122.5  grams  48  grams  74.5  grams 


48  CHEMISTRY  AND   DAILY  LIFE 

There  are  really  only  three  different  types  of  chemical 
change  possible,  namely : 

(1)  When  two  or  more  substances  unite  to  form  one  new 
substance,  as  in  reactions  (1),  (2),  and  (3)  above.     These  are 
all  examples  of  synthesis. 

(2)  When  two  or  more  substances  are  formed  by  decom- 
position of  a  single  substance,  as    in    reaction  (6)  above. 
This  may  be  termed  analysis,  as  contrasted  with  synthesis. 

(3)  When  two  or  more  substances  react  with  one  another 
to  form  two  or  more  new  substances,  as  in  reactions  (4)  and 
(5).     These  are  also  termed  cases  of  double  decomposition. 

Chemical  symbols,  then,  are  a  great  aid  in  that  they  indi- 
cate the  chemical  composition  of  a  compound  at  a  glance. 
It  must,  of  course,  be  kept  in  mind  that  such  symbols  are 
only  the  expression  of  facts  found  out  by  experiment,  and  so 
the  formula  of  a  compound  cannot  be  written  till  after  its  com- 
position has  been  actually  ascertained  by  chemical  analysis. 

The  formation  of  salts  really  appears  much  simpler  when 
expressed  by  means  of  equations  in  which  chemical  symbols 
are  used,  thus : 

KOH        +     HNO3    =       KNO3       +     H2O 

potassium  hydroxide        nitric  acid      potassium  nitrate  water 

or  potash  lye  or  saltpeter 

2  NaOH      +     H2SO4      =     Na2SO4        +  2  H2O 

sodium  hydroxide       sulphuric  acid       sodium  sulphate  water 

or  soda  lye 

Ca(OH)2        +     2  HC1     =        CaCl2        +  2  H2O 

calcium  hydroxide        hydrochloric        calcium  chloride  water 

or  slaked  lime  acid 

In  regarding  the  last  three  equations  it  will  be  seen  that 
an  acid  is  a  compound  containing  hydrogen  which  may  be 
replaced  by  a  metal,  thus  forming  a  salt.  So  potassium  ni- 
trate, sodium  sulphate,  and  calcium  chloride  are  typical 


ACIDS,  ALKALIES,  SALTS,  CHEMICAL  FORMULAS     49 

salts.  Now  the  hydroxides  of  potassium,  sodium,  and 
calcium  are  typical  bases.  A  base  is  a  compound  (usually 
an  hydroxide  of  a  metal)  which  upon  reacting  with  an  acid 
forms  a  salt  and  water.  And  finally  a  salt  is  a  compound 
formed  when  a  base  acts  upon  an  acid.  We  may  consider 
salts  as  the  products  formed  when  the  hydrogen  of  an  acid 
is  replaced  by  a  metal  or  some  group  of  elements  that  may 
play  the  role  of  a  metal  so  far  as  the  process  of  a  salt  formation 
is  concerned. 

Common  salt,  NaCl,  may  be  formed  by  direct  union  of 
sodium  and  chlorine,  thus  : 

Na  +  Cl  =  NaCl 

or  by  neutralization  of  the  base,  sodium  hydroxide,  NaOH, 
by  hydrochloric  acid,  thus  : 

NaOH  +  HC1  =  NaCl  +  H2O 

Calcium  sulphate,  CaS04,  may  be  formed  by  the  union 
of  lime,  CaO,  with  sulphuric  anhydride,  SO3,  thus : 

CaO  +  SO3  =  CaSO4 

or  by  the  action  of  slaked  lime  on  sulphuric  acid,  thus : 
Ca(OH)2  +  H2S04  =  CaS04  +  2  H2O 

The  metals,  then,  are  in  general  base-forming  substances,  and 
the  non-metals  are  acid-forming  substances,  though  some  metals 
may  at  times  act  as  acid-forming  elements,  and  some  of  the 
non-metals  may  exhibit  basic  properties. 

Among  the  most  common  salts  are  chlorides,  sulphates, 
nitrates,  carbonates,  phosphates,  and  silicates.  These  may 
be  considered  as  derived  respectively  from  the  following 
acids:  hydrochloric  acid  HC1,  sulphuric  acid  H2SO4,  nitric 
acid  HNO3j  carbonic  acid  H2CO3,  phosphoric  acid  H3PO4, 


50  CHEMISTRY  AND   DAILY  LIFE 

and  silicic  acid  H2SiO3.  So,  for  example,  we  have  sodium 
chloride  NaCl,  calcium  chloride  CaCl2,  potassium  chloride 
KC1,  magnesium  chloride  MgCl2,  ferric  chloride  FeCl3, 
cupric  chloride  CuCl2,  etc.,  all  of  which  may  be  considered 
as  derived  from  hydrochloric  acid  HC1,  the  hydrogen  of 
which  is  replaced  by  the  respective  metals.  Again,  we  have 
sodium  sulphate  Na2SO4,  potassium  sulphate  K2SO4,  am- 
monium sulphate  (NH4)2SO4,  copper  sulphate  CuSO4,  cal- 
cium sulphate  CaSO4,  magnesium  sulphate  MgSO4,  ferrous 
sulphate  (also  commonly  called  copperas)  FeSO4,  etc.  These 
sulphates  may  all  be  considered  as  derived  from  sulphuric 
acid  H2SO4,  whose  hydrogen  has  been  replaced  by  the  metals 
or  the  ammonium  group  respectively.  Similarly  we  have 
potassium  nitrate  KNO3,  sodium  nitrate  NaNO3,  calcium 
nitrate  Ca(NO3)2,  copper  nitrate  Cu(NO3)2,  ammonium 
nitrate  NH4NO3,  etc.,  all  of  which  may  be  regarded  as 
derived  from  nitric  acid  HNO3.  The  carbonates  like  so- 
dium carbonate  Na2CO3,  potassium  carbonate  K2CO3, 
ammonium  carbonate  (NH)2CO3,  calcium  carbonate  CaCO3, 
lead  carbonate  PbCO3,  etc.,  may  be  considered  as  derivatives 
of  carbonic  acid  H2CO3.  The  phosphates  like  calcium 
phosphate  Ca3(PO4)2,  sodium  phosphate  Na2HPO4,  potas- 
sium phosphate  K2HPO4,  ferric  phosphate  FePO4,  may  all 
be  regarded  as  derived  from  phosphoric  acid  H3PO4 ;  whereas 
silicates  like  sodium  silicate  Na2SiO3,  calcium  silicate  CaSiO3, 
etc.,  may  be  considered  as  derivatives  of  silicic  acid.  In 
like  manner  acetates  are  derived  from  acetic  acid,  arsenates 
from  arsenic  acid,  lactates  from  lactic  acid,  tartrates  from 
tartaric  acid,  oleates  from  oleic  acid,  borates  from  boric 
acid,  and  so  on.  Each  acid  is,  then,  capable  of  forming  a 
series  of  salts  which  result  when  the  hydrogen  of  the  acid  is 
replaced  by  the  various  metals  or  radicals  (i.e.  groups  of  ele- 
ments like  ammonium,  NH4)  that  may  act  as  metals.  In  turn 


ACIDS,  ALKALIES,  SALTS,  CHEMICAL  FORMULAS     51 

each  metal  may  form  a  series  of  salts  as  that  metal  replaces  the 
hydrogen  of  the  various  acids.  So,  for  instance,  we  have  the 
chloride  of  copper,  the  nitrate  of  copper,  the  sulphate  of 
copper,  the  borate  of  copper,  the  oleate  of  copper,  the  phos- 
phate of  copper,  the  silicate  of  copper,  etc.  Each  metal 
may  in  general  form  a  similar  long  list  of  salts  with  the  various 
acids. 

QUESTIONS 

1.  Define  the  terms  acid,  base,  salt,  and  give  an  example  of  each. 

2.  Mention  six  acids  found  in  nature,  stating  where  they  occur. 

3.  What  is  an  alkali  ?     Give  four  examples. 

4.  Write  the  equation  expressing  the  neutralization  of  hydro- 
chloric acid  by  caustic  soda. 

5.  Explain  the  meaning  of  the  following  symbols :  H,  0,  Co,  P, 
Cl,  N,  K,  Hg,  Au,  Pt,  S. 

6.  What  is  the  law  of  definite  proportions  ? 

7.  What  is  the  meaning  of  the  following  formulas  :  H20,  NaCl, 
P205,  C12H22On? 

8.  How  much  ferrous  sulphide,  FeS,  may  be  formed  from  200 
grams  of  sulphur  ?     How  many  pounds  would  this  be  ? 

9.  How  much  common  salt,  NaCl,  would  be  obtained  when 
2  pounds  of  sodium  are  burned  in  chlorine  ? 

10.  How  much  lime,  CaO,  would  be  required  to  produce  1000 
grams  of  chalk,  CaCOs  ? 


CHAPTER  VI 
THE  HALOGENS 

t  THE  elements  fluorine,  chlorine,  bromine,  and  iodine  are 
called  the  halogens.  They  never  occur  in  nature  in  the 
uncombined  state,  but  they  are  frequently  met  in  compounds. 
Fluorine  is  found  chiefly  as  calcium  fluoride,  fluor  spar, 
CaF2,  but  it  is  after  all  fairly  widely  distributed  in  minute 
amounts  in  granitic  rocks,  being  a  minor  constituent  of  the 
mineral  apatite,  which  consists  essentially  of  calcium  phos- 
phate-plus a  small  percentage  of  calcium  fluoride.  Fluorine 
is  present  in  extremely  small  quantities  in  soils,  from  which 
it  gets  into  plants,  and  so  into  animals.  In  the  enamel  of 
the  teeth  of  the  latter  notable  amounts  of  fluorine  are  always 
present.  By  treating  calcium  fluoride  with  sulphuric  acid 
hydrogen  fluoride,  hydrofluoric  acid,  HF,  is  formed,  thus : 

CaF2       +      H2SO4       =        CaSO4      +       2  HF 

calcium  sulphuric  calcium  hydrofluoric 

fluoride  acid  sulphate  acid 

This  acid  is  a  gas  which  readily  dissolves  in  water.  It 
attacks  glass,  sand,  and  silicates  in  general,  forming  silicon 
fluoride,  which  is  volatile,  and  metallic  fluorides  with  any 
bases  that  may  be  present.  Thus  its  action  on  calcium 
silicate  is  shown  by  the  following  equation : 

CaSiO3     +     6HF     =     CaF2     +     SiF4     +     3  H2O 

calcium  hydrofluoric  calcium  silicon  water 

silicate  acid  fluoride        tetrafluoride 

52 


THE  HALOGENS  53 

Hydrofluoric  acid  is  poisonous.  The  gas  and  also  the  aque- 
ous solution  of  the  latter  are  used  for  etching  glass,  —  dia- 
mond ink.  Hydrofluoric  acid  is  also  used  in  the  laboratory 
for  the  purpose  of  decomposing  silicates  in  chemical  analysis. 
Fluorine  itself  may  be  obtained  by  passing  the  electric 
current  through  a  solution  of  potassium  fluoride  and  hydro- 
fluoric acid  in  water.  Fluorine  is  a  light-colored  greenish 
yellow  gas  of  extremely  pungent  odor.  It  unites  with  all 
elements  directly,  except  with  oxygen.  It  is  probably  the 
most  active  of  all  of  the  chemical  elements. 

Chlorine  is  found  mainly  in  common  salt,  sodium  chloride, 
XaCl,  the  occurrence  of  which  will  be  discussed  in  connection 
with  sodium.  By  treating  common  salt  with  sulphuric  acid, 
hydrochloric  acid  is  formed,  thus : 

NaCl      +      H2SO4      =       NaHSO4      +      HC1 

sodium  sulphuric  sodium  acid  hydrochloric 

chloride  acid  sulphate  acid 

Hydrochloric  acid,  also  called  muriatic  acid  or  spirit  of  salt, 
is  a  colorless  pungent  gas,  which  fumes  in  the  air,  for  it  has  a 
strong  affinity  for  water  and  condenses  the  latter  from  the 
air  to  drops.  Thus  the  fumes  are  really  minute  droplets 
of  a  solution  of  hydrochloric  acid  gas  in  water.  At  ordinary 
temperatures  and  atmospheric  pressure,  one  volume  of 
water  will  dissolve  about  four  hundred  volumes  of  hydro- 
chloric acid  gas.  Hydrochloric  acid  is  a  powerful  acid. 
With  bases  it  reacts,  forming  chlorides  and  water.  In  the 
human  stomach  there  is  found  a  0.33  per  cent  solution  of 
hydrochloric  acid,  which  aids  in  the  digestion  of  food. 
Hydrochloric  acid  is  made  in  large  quantities  on  a  com- 
mercial scale  in  connection  with  the  LeBlanc  soda  process 
(which  see).  The  saturated  aqueous  solution  has  the 
specific  gravity  1.19  and  contains  38  per  cent  of  pure 
hydrochloric  acid  by  weight. 


54 


CHEMISTRY  AND  DAILY  LIFE 


Chlorine  is  prepared  by  abstracting  hydrogen  from  hydro- 
chloric acid.  This  may  be  done  by  simply  passing  the 
electric  current  through  an  aqueous  hydrochloric  acid  solu- 


FIG.  12.  —  A  carboy  of  hydrochloric  acid. 

tion,  whereupon  chlorine  is  evolved  on  one  pole  and  hydro- 
gen on  the  other.  The  common  way,  however,  is  to  oxidize 
hydrochloric  acid  by  means  of  a  suitable  oxidizing  agent. 
As  such  manganese  dioxide  is  usually  chosen,  thus  : 


Mn02 

manganese 
dioxide 


4HC1     =     MnCl2 


hydrochloric 
acid 


manganous 
chloride 


H2O 

water 


C12 

chlorine 


THE  HALOGENS  55 

The  manganese  dioxide  and  hydrochloric  acid  are  gently 
heated  together  in  a  flask  or  retort.  Chlorine  is  a  greenish 
yellow  gas  with  a  very  pungent  odor.  It  is  extremely  active 
chemically,  forming  chlorides  with  many  of  the  elements 
by  direct  union.  So  with  sodium  it  forms  sodium  chloride, 
XaCl  ;  with  copper,  cupric  chloride,  CuCl2  ;  with  phos- 
phorus, phosphorus  chloride,  PC13;  with  sulphur,  sulphur 
chloride,  S2C12  ;  etc.  On  water  chlorine  reacts  in  the  sunlight, 
forming  oxygen  and  hydrochloric  acid,  thus  : 

H2O  +  C12  =  2  HC1  +  O 

The  oxygen  thus  set  free  oxidizes  many  substances,  destroy- 
ing colors,  microorganisms,  etc.  For  this  reason  chlorine 
water  (a  solution  of  chlorine  gas  in  water)  is  a  bleaching 
agent  and  an  antiseptic.  When  chlorine  gas  is  conducted 
into  slaked  lime,  so-called  chloride  of  lime,  bleaching  powder, 
is  formed,  thus  : 

Ca(OH)2     +     C12     =     CaCl(OCl)     +    H2O 

slaked  lime  chlorine          chloride  of  lime  water 

bleaching  powder 

Bleaching  powder  is  a  powerful  antiseptic  and  bleaching 
agent.  Its  action  depends  upon  the  fact  that  it  will  readily 
yield  its  oxygen  and  pass  over  into  calcium  chloride, 
CaCl2,  thus  : 


The  oxygen  destroys  the  color  of  many  dyestuffs,  and  also 
kills  microorganisms.  Bleaching  powder  is  manufactured 
on  a  large  scale  commercially,  and  is  used  in  bleaching 
fabrics,  paper  pulp,  etc.  It  is  also  used  to  rid  the  soil  of 
undesirable  organisms. 

Bromine  is  mainly  found  as  sodium  bromide,  NaBr,  in 
connection  with  sodium  chloride.  It  may  be  prepared  by 
methods  that  are  entirely  similar  to  those  used  in  making 


56  CHEMISTRY  AND  DAILY  LIFE 

chlorine.  Thus  hydrobromic  acid  is  formed  when  sulphuric 
acid  acts  on  sodium  bromide : 

NaBr      +       H2SO4       =       NaHSO4      +      HBr 

sodium  sulphuric  acid  sodium  hydrobromic 

bromide  acid  sulphate  acid 

By  treating  manganese  dioxide  with  hydrobromic  acid, 
bromine  is  obtained : 

MnO2     +     4  HBr     =     2  H2O     +     MnBr2     +     Br2 

manganese         hydrobromic  water  manganous          bromine 

dioxide  acid  bromide 

Bromine  forms  bromides  by  direct  union  with  many  of  the 
elements.  Potassium  bromide,  KBr,  is  used  in  medicine  and 
photography.  Bromine  itself  is  a  brownish  liquid  of  sp.  gr. 
3.188  at  0°.  It  boils  at  59°  C.  About  250,000  pounds  of  it 
are  produced  yearly  in  the  United  States.  It  is  used  as  an 
antiseptic,  also  in  making  aniline  dyes,  bromides,  etc. 
Hydrobromic  acid  when  pure  is  a  colorless  gas  soluble  in 
water.  Its  properties  are  similar  to  those  of  hydrochloric 
acid,  but  it  is  weaker  than  the  latter.  Bromine  is  set  free 
from  bromides  by  chlorine,  thus  : 

NaBr        +        Cl  NaCl         +        Br 

sodium  chlorine  sodium  bromine 

bromide  chloride 

Bromine  turns  starch  paste  yellow. 

Iodine  is  found  in  the  ashes  of  sea  weeds,  also  as  sodium 
iodate,  NaIO3,  in  connection  with  Chili  saltpeter.  Iodine 
is  a  crystalline,  grayish  black  solid  having  almost  a  metallic 
luster.  It  dissolves  sparingly  in  water,  but  copiously  in 
alcohol.  The  alcoholic  solution  is  called  tincture  of  iodine. 
It  is  used  in  medicine  as  an  antiseptic  and  counter  irritant. 
With  the  metals  and  some  of  the  other  elements  iodine 
forms  iodides.  Thus  we  have  sodium  iodide  Nal,  potassium 
iodide  KI,  silver  iodide  Agl,  calcium  iodide  CaI2,  phosphorus 


THE   HALOGENS  57 

iodide  Pis,  etc.  From  sodium  iodide,  iodine  may  readily 
be  obtained  by  treatment  with  sulphuric  acid.  Thus  hydro- 
gen iodide,  hydriodic  acid,  HI,  is  formed,  which,  however, 
at  once  attacks  the  sulphuric  acid  present,  forming  sul- 
phorous  acid,  H2SO3,  and  water,  thus  : 

Nal      +      H2SO4      =       NaHSO4      +       HI 

sodium  sulphuric  acid  sodium  hydriodic 

iodide  acid  sulphate  acid 

and 

H2SO4       +      2  HI      =       H2S03     +     H2O     +     21 

sulphuric  hydriodic  sulphurous  water  iodine 

acid  acid  acid 

Iodine  turns  starch  paste  blue.  This  fact  is  used  in  testing 
for  starch.  It  is  evident  that  one  may  also  use  starch  paste 
in  testing  for  iodine.  The  vapors  of  iodine  are  of  a  beautiful 
violet  color,  from  which  fact  the  element  has  received  its  name. 

The  thyroid  gland  contains  iodine  in  the  form  of  a  complex 
compound,  thyroiodine.  In  the  treatment  of  goiter  and  other 
diseases  connected  with  the  thyroid  gland,  iodine  compounds, 
like  potassium  iodide,  or  extract  of  the  thyroid  gland  of  the 
sheep,  are  frequently  prescribed  by  the  physician. 

Iodine  may  be  liberated  from  iodides  by  treating  the  latter 
with  bromine  or  chlorine,  thus  : 

KI        +        Cl  KC1        +        I 

potassium  chlorine  potassium  iodine 

iodide  chloride 

QUESTIONS 

1.  Name  the  halogens,  and  one  important   compound  of  each 
found  in  nature. 

2.  (a)  How  may  hydrofluoric  acid  be  prepared  ? 
(6)  What  use  is  made  of  this  compound  ? 

3.  Describe  hydrochloric  acid  and  tell  how  it  is  prepared. 

4.  What   is  hydrochloric   acid   used   for?    What  other  names 
does  this  compound  have  ? 


58  CHEMISTRY  AND   DAILY  LIFE 

5.  How  may  chlorine  be  made  ?     Describe  this  element. 

6.  Explain  how  chlorine  bleaches. 

7.  What  is  bleaching  powder  ?    Upon  what  fact  does  its  action 
depend  ? 

8.  What  use  is  made  of  bromine  ?     How  may  it  be  prepared  ? 

9.  Compare  the  properties  of  iodine  with  those  of  the  other 
elements. 

10.  Mention  some  of  the  uses  of  iodine.  Compute  how  much 
iodine  would  be  obtained  when  100  grams  of  chlorine  act  upon  an 
excess  of  potassium  iodide. 


CHAPTER  VII 

SULPHUR,  PHOSPHORUS,  ARSENIC,  ANTIMONY,   AND 

BISMUTH 

Sulphur  is  found  in  nature  in  the  free  or  uncombined 
state  in  large  quantities.  The  largest  deposits  occur  in 
Sicily,  Texas,  and  Louisiana.  Sulphur  was  well  known 
even  in  ancient  times.  It  frequently  occurs  around  the 
brims  of  craters  of  volcanoes,  and  so  is  also  called  brimstone. 
In  the  market  it  may  be  obtained  in  sticks  as  roll  sulphur, 
and  also  in  powdered  form  as  "  flowers  of  sulphur."  Sul- 
phur melts  at  114°. 5,  forming  a  lemon-colored  liquid,  which 
on  further  heating  turns  brown  and  becomes  viscous  at  about 
160°  to  200°  C.  Finally  on  further  heating  this  liquid  again 
becomes  limpid  and  boils  at  450°  C.,  giving  off  brown  vapors. 
Sulphur  will  burn  in  the  air  or  in  oxygen,  forming  sulphur 
dioxide,  thus :  g  +  Q2  =  SQ2 

Sulphur  dioxide  is  a  gas  of  suffocating  odor.     In  it  living 
beings  cannot  exist,  and  so  it  is  used  as  a  disinfecting  agent. 
As  such  it  is  cheap.     It 
is  very   commonly  used 
in  fumigating  rooms  and 
houses  .that   have   been 
occupied  by  persons  hav- 
ing   Contagious    diseases.          FIG.  13:— A  can  filled  with  liquid  sul- 
phur dioxide. 

tor  this  purpose  it  may 

be  had  on  the  market  in  liquid  form  in  tin  cans,  Fig.  13. 
These  are  soldered  shut  and  have  a  small  short  lead  tube 
attached  to  them,  the  end  of  which  can  be  nipped  off.  The 

59 


60 


CHEMISTRY  AND   DAILY  LIFE 


gas  can  then  make  its  escape  into  the  room.  The  latter 
should  be  kept  tightly  closed  for  several  hours  after  it  has 
been  filled  with  sulphur  dioxide.  The  gas  may  also  be  pre- 
pared by  burning  sulphur  in  the  rooms  to  be  disinfected. 
Care  must  be  taken  in  this  process  not  to  set  the  house  on 
fire  (see  Chapter  XXI). 

Sulphur  dioxide  is  also  used  as  a  bleaching  agent.      It  is 
especially   used   for   bleaching   straw,  feathers,  and   fabrics 


FIG.  14.  — Pumping  sulphur  from  a  Louisiana  sulphur  well. 


SULPHUR,   PHOSPHORUS,   ARSENIC,   ANTIMONY      61 

that  would  be  injured  by  bleaching  powder.  It  used  to 
be  employed  also  in  bleaching  food  products,  such  as 
dried  apples,  and  grains  discolored  by  fire,  for  example; 
but  this  is  not  to  be  recommended  on  account  of  the 
poisonous  nature  of  the  substance.  Sulphur  dioxide  bleaches 
by  uniting  chemically  with  the  substance  whose  color  is 
altered.  The  action  is  thus  quite  different  from  that  of 
bleaching  with  either  hydrogen  peroxide  or  bleaching 
powder,  which  bleach  because  of  oxidation  of  the  coloring 
matter. 

Sulphur  is  also  used  in  making  fireworks,  black  gunpowder, 
both  soft  and  hard  rubber,  carbon  bisulphide,  lime  sulphur 
mixtures  for  spraying  shrubs  and  trees,  and  sulphuric  acid. 
Thousands  of  tons  of  the  latter  compound  are  produced 
annually.  In  its  production  sulphur  is  first  converted  into 
sulphur  dioxide  by  burning  it  in  the  air.  The  sulphur 
dioxide  is  then  mixed  with  air  and  this  mixture  is  passed 
over  finely  divided  platinum  heated  from  400°  to  450°  C. 
In  contact  with  this  hot,  finely  divided  platinum  the  sulphur 
dioxide  unites  further  with  the  oxygen  of  the  air,  forming 
sulphur  trioxide,  thus : 

SO2  +  O  =  SO3 

Sulphur  trioxide  forms  long,  white,  crystalline  fibers,  which 
melt  at  14°.8  C.  It  takes  on  water  very  greedily,  forming 
sulphuric  acid,  thus : 

SO3  +  H20  =  H2SO4 

Sulphuric  acid,  also  called  oil  of  vitri61,  is  a  heavy  viscous 
liquid,  being  1.838  times  as  heavy  as  water  at  15°  C.  It  has 
great  affinity  for  water  and  will  dissolve  in  the  same  with 
liberation  of  much  heat.  Care  must  consequently  be  used  in 
pouring  sulphuric  acid  into  water.  Always  pour  the  acid 


62  CHEMISTRY  AND   DAILY  LIFE 

gradually  into  the  water  (never  the  water  into  the  acid)  and 
stir  well  after  each  addition  of  acid.  If  the  water  is  poured 
into  the  acid,  or  if  too  much  of  the  acid  is  poured  into  the 
water  at  a  time,  the  heat  evolved  is  so  great  that  liquid  is 
liable  to  be  thrown  out  of  the  container  and  injure  the  per- 
son. Sulphuric  acid  is  a  very  important  article  of  com- 
merce. With  most  of  the  metals,  ammonia,  and  other  basic 
substances,  it  forms  salts  called  sulphates.  Thus  we  have 
copper  sulphate  CuS04,  calcium  sulphate  CaSO4,  barium 
sulphate  BaSO4,  ammonium  sulphate  (NH4)2SO4,  etc.  Be- 
sides its  ability  to  unite  with  basic  substances  to  form  sulphates, 
the  most  striking  property  of  sulphuric  acid  is  its  attraction 
for  water,  which  has  already  been  mentioned.  So  great  is 
the  affinity  of  sulphuric  acid  for  water  that  it  will  abstract 
the  latter  from  wood,  sugar,  starch,  meat,  and  in  fact  from 
all  other  animal  and  vegetable  substances,  thus  charring 
them.  Sulphuric  acid  is  further  used  in  making  super- 
phosphate fertilizers,  in  preparing  hydrochloric  acid  and  soda 
by  the  LeBlanc  soda  process,  in  manufacturing  ether,  aniline 
dyes,  guncotton,  dynamite,  smokeless  powder,  and  many  other 
compounds  in  which  a  strong  drying  agent  is  required.  Up- 
wards of  four  million  tons  of  sulphuric  acid  are  manufactured 
annually.  Besides  the  process  of  making  sulphuric  acid, 
which  has  already  been  described  and  which  is  known  as  the 
contact  process,  sulphur  dioxide  is  also  oxidized  by  means 
of  nitric  acid  and  oxides  of  nitrogen  in  the  presence  of  water 
vapor.  This  is  an  older  process  which  is  carried  on  in  lead- 
lined  chambers,  lead  being  but  very  slightly  attacked  by 
sulphuric  acid.  The  lead  chamber  process  is  still  used  to 
a  large  extent,  especially  for  making  sulphuric  acid  of  60  to 
78  per  cent  strength. 

Sulphuric  acid  will  react  with  many  salts,  forming  sulphates 
and  liberating  the  acids  of  such  salts,  thus  : 


SULPHUR,   PHOSPHORUS,  ARSENIC,   ANTIMONY     63 
NaCl        +        H2S04       =     NaHS04     +        HC1 

sodium  chloride  sulphuric  acid  acid  sodium  hydrochloric 

sulphate  acid 

KN03       +    H2SO4    =       KHS04       +      HNO3 

potassium  nitrate  potassium  acid  nitric  acid 

sulphate 

Fuming  sulphuric  acid,  also  called  Nordhausen  sulphuric 
acid,  is  sulphuric  acid  in  which  additional  sulphur  trioxide 
has  been  dissolved. 

Sulphurous  acid  is  formed  when  sulphur  dioxide  dissolves 
in  water,  thus  :  SQ2  +  HaO  =  jj^ 

From  it  salts  called  sulphites  are  derived.  Thus  we  have 
sodium  sulphite  Na2SO3,  sodium  acid  sulphite,  also  called 
sodium  bisulphite,  NaHS03,  calcium  sulphite  CaSO3,  etc. 
The  sulphites  are  used  in  photography  and  in  the  preparation 
of  wood  pulp  in  the  paper  industry.  Sulphites  also  used  to 
be  employed  as  food  preservatives,  but  this  is  now  for- 
bidden by  law,  for  they  are  injurious  to  health. 

Hydrogen  sulphide  is  a  compound  consisting  of  hydro- 
gen and  sulphur.  Its  composition  is  expressed  by  the 
formula  H2S.  This  gas  is  formed  in  rotten  eggs,  in  manure 
pits,  and  wherever  animal  and  vegetable  matter  is  decaying 
without  proper  access  of  air.  Hydrogen  sulphide  is  poi- 
sonous. It  dissolves  in  water,  one  volume  of  the  latter 
absorbing  about  three  volumes  of  the  gas.  Hydrogen  sul- 
phide is  1.19  times  as  heavy  as  air.  It  will  burn,  forming 
water  and  sulphur  dioxide,  thus : 

H2S  +  3  O  =  H20  +  S02 

Hydrogen  sulphide  may  be  prepared  by  treating  ferrous 
sulphide  with  hydrochloric  or  sulphuric  acid,  thus : 

FeS  +  2  HC1  =  FeCl2  +  H2S 
FeS  +  H2S04  =  FeS04  +  H2S 


64  CHEMISTRY  AND  DAILY  LIFE 

When  introduced  into  solutions  of  salts  of  the  heavy  metals, 
hydrogen  sulphide  forms  characteristic  precipitates  consisting 
of  the  sulphides  of  the  metals,  and  it  is  consequently  much  used 
in  testing  for  heavy  metals  in  chemical  analysis,  thus : 

CuS04  +  H2S    =   CuS  +  H2S04 

copper 
sulphide 

2  AsCl3  +  3  H2S  =  As&  +  6  HC1 

arsenious 
sulphide 

Carbon  bisulphide  is  a  colorless  liquid  of  specific  gravity 
1.26.  It  boils  at  47°  and  is  very  inflammable.  Its  vapors 
mixed  with  air  are  explosive,  and  consequently  no  flame  or 
spark  must  be  present  when  carbon  bisulphide  is  being  used. 
It  will  riot  dissolve  in  water.  It  is  used  as  a  solvent  for  fats 
and  oils,  also  for  the  extermination  of  ants  and  other  insect 
pests.  Carbon  bisulphide  is  prepared  by  heating  carbon 
and  sulphur  together  out  of  contact  of  the  air,  usually  in  an 
electric  furnace.  The  gas  formed  is  then  condensed  by 
means  of  cold  water. 

Sulphur  occurs  in  nature  also  as  calcium  sulphate  CaSO4, 
gypsum  CaS04 . 2  H2O,  and  also  in  combination  with  metals 
as  sulphides  like  iron  pyrites  or  fool's  gold  FeS2,  sulphide  of 
lead  or  galenite  PbS,  zinc  sulphide  or  black  jack  ZnS,  etc. 
From  pyrites  sulphur  dioxide  is  obtained  by  heating  the 
mineral  in  the  air.  Much  of  the  sulphur  dioxide  used  in  the 
manufacture  of  sulphuric  acid  is  obtained  from  this  source. 
Nearly  two  and  one  half  million  tons  of  gypsum  are  pro- 
duced annually  in  the  United  States  alone.  It  is  used  as 
land  plaster,  as  wall  plaster,  stucco,  etc. 

Finally  all  plants  and  animals  contain  sulphur.  With- 
out it  they  could  not  live.  Sulphur  is  a  constituent  of  albumen. 
Thus  muscular  tissues,  horns,  hoofs,  hair,  nerves,  eggs,  and 
seeds  contain  sulphur.  In  urine  sulphur  is  present  in  the 


SULPHUR,   PHOSPHORUS,   ARSENIC,   ANTIMONY     65 

form  of  sulphates,  for  as  the  animal  lives,  the  sulphur  com- 
pounds in  its  tissues  are  continually  oxidized  to  sulphates, 
which  are  then  eliminated  by  means  of  the  kidneys.  Some 
plants,  like  onions,  garlic,  mustard,  skunk  cabbages,  radishes, 
contain  odoriferous  sulphur  compounds.  In  order  to  thrive 
well  they  require  a  soil  which  contains  an  adequate  amount 


FIG.  15.  — A  group  of  sulphur  crystals  on  limestone. 

of  sulphur.  When  plants  and  animals  decay,  the, sulphur 
compounds  they  contain  gradually  decompose,  forming 
hydrogen  sulphide  when  the  sulphur  is  relatively  abun- 
dant and  access  to  the  air  is  limited,  and  sulphates  when 
there  is  proper  access  of  air.  When  these  sulphates  are 
again  put  into  the  soil,  as  in  manuring  or  in  treating  with 
land  plaster  (i.e.  gypsum),  the  rootlets  of  plants  again 
take  them  up,  and  transform  them  into  the  various  sulphur 

F 


66 


CHEMISTRY  AND  DAILY  LIFE 


compounds  of  their  tissues,  and  thus  the  sulphur  cycle  is 
completed. 

Sulphur  springs  contain  hydrogen  sulphide,  which  is 
easily  detected  by  its  foul  odor.  Many  mineral  waters 
contain  calcium  sulphate,  some  contain  sodium  sulphate, 
Na2SO4,  others  like  those  at  Epsom  contain  magnesium 
sulphate,  MgSO4.  The  latter  are  bitter  to  the  taste  and 
have  a  laxative  effect.  Magnesium  sulphate  is  called  Epsom 
salt,  and  is  sometimes  taken  as  a  purgative. 

Phosphorus  never  occurs  in  nature  in  the  free  state.  It 
is,  however,  quite  widely  distributed  in  small  quantities  in 

compounds.  It  occurs 
as  calcium  phosphate, 
Ca3(PO4)2,  in  phosphate 
rock  in  the  Carolinas  and 
some  of  the  Western 
states.  Small  amounts 
of  phosphates  occur  also 
in  all  fertile  soils,  in  iron 
ores  (from  which  it  passes 
into  blast  furnace  slags 
when  the  ores  are  re- 
duced), and  in  many 
granitic  rocks,  clays,  etc. 
Bones  consist  of  calcium 
phosphate  to  the  extent  of 
about  80  per  cent.  Phos- 
phorus is  an  important  and  indispensable  part  of  the  tissues 
of  all  plants  and  animals.  In  the  nerves,  brain,  blood, 
muscles,  and  in  fact  in  all  animal  parts  that  are  concerned 
in  locomotion  or  reproduction,  phosphorus  is  found.  In 
seeds  phosphorus  is  always  present,  particularly  in  the 
embryos,  and  without  phosphorus  plants  cannot  grow,  hence 


FIG.  16.  — A  piece  of  phosphate  rock. 


SULPHUR,   PHOSPHORUS,   ARSENIC,   ANTIMONY     67 


its  importance  in  the  soil.  In  the  bodies  of  plants  and 
animals  phosphorus  is  combined  with  carbon,  hydrogen, 
oxygen,  nitrogen,  and  sulphur.  The  nerves  and  the 
brain  are  especially  rich  in  a  complex  compound,  leci- 
thine,  whose  composition  is  expressed  by  the  formula 


FIG.  17.  —  Barley  growing  with  and  without  proper  food. 


( 1 )  Complete  manure. 
(4)  No  potassium. 


(2)  No  nitrogen. 
(5)  No  calcium. 


(3)  No  phosphorus. 
(6)  No  magnesium. 


68  CHEMISTRY  AND  DAILY  LIFE 

.  As  animals  live  these  complex  compounds  are  gradually 
oxidized,  phosphates  being  formed,  which  are  then  eliminated 
by  the  kidneys.  Thus  urine  always  contains  phosphates, 
especially  calcium  and  potassium  phosphates.  When  these 
are  then  returned  to  the  land  as  fertilizer,  they  are  again 
taken  up  by  the  roots  of  plants  and  converted  into  complex 
phosphorus  compounds  in  their  tissues  and  seeds.  These  in 
turn  are  eaten  by  animals,  and  so  the  phosphorus  cycle  com- 
pletes itself.  It  is  clear,  however,  that  considerable  amounts 
of  phosphorus  are  never  returned  to  the  land,  being  washed 
away  continually  together  with  other  valuable  fertilizer 
material  into  the  waterways,  which  finally  empty  into  the 
ocean.  The  sewage  of  our  large  cities  in  particular  represents 
a  colossal  waste.  In  order  to  keep  up  the  supply  of  phosphorus, 
bones,  blast  furnace  slags,  and  ground  phosphate  rock  are 
employed  as  fertilizers.  When  bones  are  treated  with  sul- 
phuric acid,  so-called  superphosphate  is  produced,  thus : 

Ca3(P04)2     +     2H2SO4     =     2  CaSO4  +  CaH4(PO4)2 

calcium  phosphate         sulphuric  acid  superphosphate 

This  is  more  soluble  in  the  waters  of  the  soil  and  hence  more 
available  to  plants. 

Phosphorus  itself  is  produced  by  heating  calcium  phosphate 
with  silica  (sand)  and  carbon.  These  are  finely  ground  and 
intimately  mixed  and  then  heated  out  of  contact  with  the 
air  in  earthenware  retorts  or  in  a  suitable  electric  furnace. 
The  following  change  takes  place  : 

Ca3(PO4)2  +  3  SiO2  +  5  C  =   3  CaSiO3  +  5  CO  +  2  P 

calcium  silica  carbon  calcium  carbon          phos- 

phosphate  silicate  monoxide     phorus 

Phosphorus  is  a  yellowish,  translucent,  waxlike  solid. 
Under  water  it  may  be  melted  at  44°  C.  It  catches  fire  in 
the  air  at  about  35°  C.,  and  hence  it  is  always  kept  and  trans- 


SULPHUR,   PHOSPHORUS,  ARSENIC,  ANTIMONY     69 

ported  out  of  contact  with  the  air,  usually  under  water  in- 
air-tight  cans.  Phosphorus  is  very  poisonous,  0.1  gram  being 
sufficient  to  produce  death  in  the  case  of  an  adult.  Phos- 
phorus burns  are  dangerous,  and  they  heal  very  slowly. 
Phosphorus  should  consequently  be  handled  with  great 
care.  Forceps  should  always  be  used  when  handling  phos- 
phorus, and  small  amounts,  usually  not  larger  than  a  pea, 
should  be  employed  in  experiments  by  the  beginner. 

Phosphorus  is  used  to  poison  rats  and  other  vermin,  and 
in  making  matches.  For  the  latter  purpose  yellow  phos- 
phorus should  not  be  employed,  for  the  workers  In  match 
factories  are  frequently  poisoned  by  working  with  it,  the 
poisoning  being  evidenced  by  an  enlargement  of  the  liver 
and  a  gradual  destruction  of  the  jawbones.  When  heated 
out  of  contact  with  the  air  to  from  250°  to  300°  C.,  yellow 
phosphorus  changes  to  a  red  powder,  called  red  phosphorus. 
This  allotropic  form  of  phosphorus  is  far  less  dangerous  than 
the  yellow  variety.  It  will  not  take  fire  in  the  air  till  heated 
to  about  200°  C.,  and  moreover  it  is  not  poisonous.  It  is 
frequently  employed  in  the  chemical  laboratory  in  preparing 
phosphorus  compounds,  and  it  is  also  used  in  making  safety 
matches.  The  latter  commonly  contain  a  mixture  of  potas- 
sium chlorate,  potassium  bichromate,  powdered  glass,  and 
glue  or  dextrine,  as  the  match  head,  whereas  on  the  friction 
surface  on  the  box  there  is  a  mixture  of  red  phosphorus, 
antimony  sulphide,  manganese  dioxide,  and  glue.  The 
powdered  glass  increases  the  friction,  which  raises  the  tem- 
perature to  the  point  at  which  the  match  head  bursts  into 
flame.  Safety  matches  ignite  only  by  rubbing  on  the  specially 
prepared  surface  on  the  box.  They  were  first  prepared  in 
Sweden  and  so  are  often  called  Swedish  matches.  Matches 
containing  yellow  phosphorus  in  the  head  will  ignite  by  rubbing 
on  any  surface.  They  are  dangerous  because  they  may  cause 


70  CHEMISTRY  AND  DAILY  LIFE 

conflagrations,  and  also  because  of  their  poisonous  nature 
many  lives  are  sacrificed  in  manufacturing  them.  Phos- 
phorus matches  first  came  into  use  in  1832,  and  now  some 
3000  tons  of  phosphorus  are  annually  used  up  in  making 
matches. 

Phosphoric  acid  is  produced  by  treating  calcium  phosphate 
with  sulphuric  acid,  thus  : 

Ca3(PO4)2     +    3H2SO4      =      3CaSO4     +     2  H3PO4 

calcium  phosphate       sulphuric  acid         calcium  sulphate     phosphoric  acid 

It  is  a  sirupy  liquid  of  specific  gravity  1.88.  It  is  a  pro- 
nounced acid  and  forms  phosphates  with  the  metals,  with 
ammonia,  and  other  bases.  On  heating  phosphoric  acid 
it  loses  water  and  forms  metaphosphoric  acid,  HPO3,  thus  : 

H3P04  =  HPO3  +  H2O 

Metaphosphoric  acid  is  analogous  to  nitric  acid,  HNO3. 

When  phosphorus  is  burned  in  the  air  or  in  oxygen,  phos- 
phorus pentoxide  P2O5  is  formed,  thus  : 

2  P  +  5  O  =  P2O5 

The  latter  on  treatment  with  water  forms  phosphoric  acid, 
thus:  P205+-3H20  =  2H3P04 

As  phosphorus  is  a  valuable  constituent  of  fertilizers,  the 
percentage  content  in  the  latter  should  always  be  considered 
in  making  purchases.  The  per  cent  of  phosphorus  is  some- 
times stated  as  per  cent  P,  which  means  the  element  itself, 
but  more  frequently  it  is  stated  on  the  label  as  per  cent 
phosphorus  pentoxide,  P2O5,  which  is  erroneously  called 
phosphoric  acid.  It  is  to  be  remembered  that  P2O5  contains 
only  62  pounds  of  phosphorus  to  80  pounds  of  oxygen. 
That  is  to  say,  it  contains  only  62  pounds  of  phosphorus  in 


SULPHUR,   PHOSPHORUS,   ARSENIC,   ANTIMONY     71 

every  142  pounds.  Dealers  like  to  express  the  phosphorus 
content  of  fertilizers  as  per  cent  of  P2O5,  for,  of  course,  the 
figure  appears  much  larger  than  when  expressed  as  per  cent  P. 

Arsenic  is  a  steel-gray  to  black,  brittle  substance  having  a 
metallic  luster.  It  burns  in  the  air  emitting  a  garlic-like 
odor  and  thus  forms  a  white  powder,  arsenious  oxide,  or 
white  arsenic,  As2O3,  which  floats  in  the  air  as  a  white  cloud. 
Indeed,  white  arsenic  is  the  most  important  compound  of 
arsenic.  It  is  quite  common  on  the  market  and  relatively 
inexpensive.  Like  all  compounds  of  arsenic,  it  is  very  poi- 
sonous. White  arsenic,  arsenious  acid,  or  "  arsenic,"  as  it  is 
also  often  called  in  commerce,  is  used  as  rat  poison.  About 
1500  tons  are  produced  yearly  in  the  United  States.  It  is 
slightly  soluble  in  water  and  has  a  sweetish,  sickening  taste. 
The  antidote  for  arsenic  poisoning  is  freshly  precipitated 
ferric  hydroxide.  This  forms  an  insoluble  mass  with  ar- 
senious oxide. 

Arsenic  compounds  are  used  almost  entirely  as  poisons  for 
vermin  and  insect  pests.  Two  compounds  of  arsenic  are  at 
present  very  commonly  employed  for  this  purpose,  namely, 
Paris  green,  whose  composition  is  Cu3As2O6 .  Cu(C2H3O2)2, 
being  a  double  salt  of  cupric  arsenite  and  cupric  acetate, 
and  lead  arsenate  Pb3(AsO4)2.  Both  Paris  green  and 
lead  arsenate  are  but  sparingly  soluble  in  water.  They 
are  used  in  exterminating  potato  bugs  and  various  other 
insects.  Directions  for  preparing  the  proper  mixtures  for 
such  spraying  will  be  given  later.  It  should  be  kept  in  mind 
that  both  compounds  are  strong  poisons  and  must  be  used  with 
proper  care. 

Antimony  is  a  brittle  metal.  It  is  used  in  making  type 
metal  and  Babbitt  metal  for  machine  bearings.  As  molten 
antimony  solidifies,  it  expands  and  fills  the  molds,  hence  it 
is  valuable  in  many  alloys ;  moreover,  it  is  hard  and  when 


72  CHEMISTRY  AND   DAILY  LIFE 

mixed  with  lead  and  tin  forms  an  alloy  which  is  particularly 
suitable  for  type,  the  composition  being  25  per  cent  anti- 
mony, 50  per  cent  lead,  and  25  per  cent  tin.  Babbitt  metal 
contains  70  to  90  per  cent  lead,  alloyed  with  tin  and  anti- 
mony. Bullets  and  shot  consist  of  lead  alloyed  with  from 
0.2  to  0.4  per  cent  arsenic. 

Bismuth,  too,  is  a  brittle  metal.  It  is  used  in  preparing 
low-melting  alloys  which  are  employed  in  making  readily 
fusible  plugs  in  the  pipes  of  automatic  sprinklers  for  fire 
protection.  So,  for  instance,  Wood's  metal,  consisting  of 
1  part  tin,  2  parts  lead,  1  part  cadmium,  and  4  parts  bismuth, 
melts  at  60°. 5  C.  Bismuth  compounds  are  used  in  medi- 
cine, the  most  common  preparation  being  bismuth  sub- 
nitrate,  BiO  .  NO3 .  BiO  .  OH,  a  white  powder  which  is  diffi- 
cultly soluble  in  water  and  practically  tasteless.  It  is  pre- 
scribed in  cases  of  dysentery  and  other  disturbances  of  the 
alimentary  canal.  It  is  also  sometimes  used  as  a  face 
powder. 

QUESTIONS 

1.  How  does  sulphur  occur  in  nature  ? 

2.  Describe  how  this  element  behaves  on  heating. 

3.  What  is  formed  when  sulphur  is  burned  in  the  air  ?     Describe 
the  properties  and  uses  of  this  substance. 

4.  What  use  is  made  of  sulphur  ? 

6.  What  are  the  two  methods  by  which  sulphuric  acid  is  manu- 
factured on  a  large  scale  ? 

6.  Describe  the  properties  of  sulphuric  acid.     What  use  is  made 
of  this  substance  ? 

7.  What    are   sulphites?    Sulphates?    Give    an    example    of 
each. 

8.  What  is  hydrogen  sulphide  ?     How  is  it  prepared  ? 

9.  How  is  carbon  bisulphide  made  ?     What  is  it  used  for  ? 
10.  Discuss  the  role  of  sulphur  in  plants  and  animals. 


SULPHUR,   PHOSPHORUS,   ARSENIC,  ANTIMONY     73 

11.  In  what  forms  is  phosphorus  found  in  nature  ? 

12.  Discuss  the  role  of  phosphorus  in  plant  and  animal  life. 

13.  What  use  is  made  of  phosphorus  in  the  arts  ? 

14.  What  is  superphosphate  fertilizer  ? 

15.  How  much  phosphoric  acid,  HsPO-i,  could  be  produced  from 
one  ton  of  calcium  phosphate,  Ca3(P04)2,  the  essential  compound  in 
phosphate  rock  ? 

16.  How  much  phosphorus  is  there  in  1  pound  of  phosphorus 
pentoxide,  P20s?     How  much  phosphoric  acid,  H3P04,  could  be 
made  from  1  pound  of  P205? 

17.  What  is  white  arsenic  ? 

18.  In  what  other  commercial  compounds  does  arsenic  occur? 
What  are  these  used  for? 

19.  How  much  arsenic  is  there  in  a  pound  of  Paris  green  ? 

20.  What  are  antimony  and  bismuth,  and  what  use  is  made  of 
them? 


CHAPTER   VIII 
BORON  AND  SILICON 

Boron  occurs  in  nature  in  boric  acid  and  its  sodium  and 
calcium  salts.  It  is  never  found  in  the  uncombined  state. 
The  element  boron  is  a  brown,  brittle  solid.  It  may  be  dis- 
solved in  molten  aluminum,  and  when  the  mass  cools  boron 
separates  out  in  form  of  crystals  that  are  almost  as  hard  as 
diamond.  Boric  acid  has  the  composition  H3BO3.  It  may 
be  prepared  from  borax,  Na2B4O7 .  10  H2O,  by  treating  a  hot 
concentrated  solution  of  the  latter  with  either  hydrochloric 
or  sulphuric  acid.  The  boric  acid  separates  out  in  the  form 
of  crystalline  flakes  on  cooling,  thus  : 


Na2B407  +     2  HC1     +    5  H2O  =  2  NaCl  +  4  H3BO3 

sodium  hydrochloric  water  sodium          boric  acid 

tretraborate  acid  chloride 

Boric  acid  and  borax  are  by  far  the  most  important  compounds 
of  boron.  Boric  acid  is  known  also  as  boracic  acid.  It 
dissolves  in  water.  At  room  temperature  the  saturated 
solution  contains  about  4  per  cent.  It  is  frequently  used  as 
an  antiseptic  wash,  especially  in  treating  the  eyes,  for  it  is 
a  very  mild  agent.  Compresses  of  saturated  boric  acid  solu- 
tion are  frequently  applied  on  parts  of  the  body  that  are  swollen 
because  of  blood  poisoning.  Powdered  boric  acid  feels  slip- 
pery to  the  touch,  and  consequently  is  at  times  used  to 
spread  on  the  floors  of  dance  halls.  It  has  also  been  used  to 
preserve  milk,  meats,  fish,  etc. ;  but  as  it  is  injurious  to  health, 
the  practice  is  now  forbidden  by  law.  Boric  acid  has  prac- 

74 


BORON  AND   SILICON 


75 


tically  no  effect  on  litmus,  for  it  is  an  extremely  weak  acid ; 
it  turns  turmeric  paper  reddish  brown,  however,  and  this 
serves  as  a  delicate  test  for  boric  acid.  When  the  turmeric 
paper  thus  reddened  is  afterward  treated  with  caustic 
alkali  solution,  it  turns  to  a  dark  greenish  black. 

Borax  is  alkaline  toward  litmus,  for  it  is  a  salt  of  a  very 
weak  acid  and  a  powerful  base.  The  salt  forms  beautiful 
crystals,  which  crumble  to  pow- 
der on  standing  in  the  air,  be- 
cause they  lose  water.  Over 
forty  thousand  tons  of  borax  are 
produced  in  the  United  States 
annually.  The  chief  deposits  of 
colemanite,  Ca2B2On  .  5  H2O, 
from  which  much  borax  is  made, 
occur  in  California  and  Oregon. 

In  the  laundry,  borax  is  used 
for  softening  water  and  for  en- 
hancing the  gloss  of  starch  in 
ironing.  It  is  also  used  as  an 
antiseptic,  as  a  mordant  in  dyeing 
fabrics,  and  as  a  flux  in  welding 
iron  and  brazing  metals  together. 
Like  boric  acid,  it  has  also  been 
used  for  preserving  foods,  but 
this  practice  is  to  be  strongly 
condemned.  In  making  glazes 
and  enamels  for  pottery  and  enameled  iron  ware,  borax  and 
boric  acid  are  often  used,  also  in  the  production  of  certain 
kinds  of  hard  glass. 

While  boron  compounds  after  all  are  found  in  relatively 
small  quantities  on  the  earth,  compounds  of  silicon  are  ex- 
tremely abundant,  for  they  make  up  by  far  the  larger  portion 


FIG.  18. — A  group  of  borax 
crystals. 


76  CHEMISTRY  AND  DAILY  LIFE 

of  the  solid  part  of  the  earth.  The  element  silicon  never 
occurs  in  the  uncombined  form.  It  is  a  brittle  solid  having 
metallic  luster.  Its  specific  gfavity  is  2.49.  It  is  so  hard 
that  one  can  scratch  glass  with  it.  It  is  now  made  on  a  large 
scale  by  heating  silicon  dioxide,  quartz  sand,  with  coke  in 
the  electric  furnace,  thus  : 

SiO2         +        2C  2  CO  +      Si 

silicon  dioxide  carbon  carbon  monoxide  silicon 

At  present  silicon  is  used  mainly  in  the  manufacture  of  steel, 
where  it  serves  as  a  reducing  agent. 


FIG.  19.  —  Molten  silicon  as  it  is  being  tapped  from  an  electric  furnace. 

Silicon  dioxide,  SiO2,  also  called  silica,  is  the  most  impor- 
tant compound  of  silicon.  Quartz,  quartzite,  flint,  chalcedony, 
opal,  amethyst,  agate,  carnelian,  sandstone,  white  sand,  espe- 
cially that  on  the  seashore  and  the  desert,  are  almost  entirely 


BORON  AND   SILICON  77 

silicon  dioxide.  Silica  is  hard  and  brittle,  and  is  much  used 
as  an  abrasive.  Sandpaper  consists  of  quartz  sand  glued 
on  paper.  Silica  may  be  melted  to  a  clear  glass  in  the  oxyhy- 
drogen  flame.  Utensils  of  such  glass  are  still  quite  costly. 
They  are  mainly  used  in  laboratories.  Although  quartz  glass 
is  quite  brittle,  it  will  not  break  when  exposed  to  sudden 
changes  of  temperature.  So  a  dish  of  quartz  glass  may  be 
made  red  hot  and  then  thrust  into  cold  water  without  break- 
ing the  dish.  Quartz  sand  is  also  employed  in  making  glass, 
porcelain,  portland  cement,  and  ordinary  lime  mortar. 


FIG.  20.  — Quartz  crystals  from  Hot  Springs,  Arkansas. 

When  pulverized  quartz  sand  is  fused  with  soda  (sodium 
carbonate),  sodium  silicate  is  formed,  thus: 

SiO2       +       Na2CO3       =      Na2SiO3       +       CO2 

silica  soda  sodium  silicate  carbon  dioxide 

water  glass 

Sodium  silicate  is  also  called  water  glass.  It  is  readily 
soluble  in  water,  and  its  solutions  are  employed  in  preserving 
eggs,  and  in  cementing  asbestos  fibers  and  asbestos  paper 
together.  When  sodium  silicate  solution  is  treated  with 


78 


CHEMISTRY  AND  DAILY  LIFE 


hydrochloric  or  some  other  strong  acid,  silicic  acid  is  formed, 
and  this  separates  from  concentrated  solutions  in  the  form 
of  flakes  or  jelly,  thus  : 


Na2Si03     +      2HC1      =      H2SiO3 

sodium  silicate      hydrochloric  acid         silicic  acid 


+       2  NaCl 

sodium  chloride 


At  ordinary  temperatures  silicic  acid  is  a  very  weak  acid. 
It  does  not  affect  litmus,  and  has  no  taste.  In  water  it  is 
but  very  slightly  soluble.  However,  when  the  sodium 
silicate  solution  used  to  prepare  the  silicic  acid  (see  above 
equation)  is  only  1  per  cent  strong,  silicic  acid  will  not 
separate  on  acidifying  with  hydrochloric  acid.  By  placing 
this  solution  in  an  animal  bladder,  like  a  hog's  bladder,  and 
immersing  this  in  a  pail  of  water,  the  sodium  chloride  and 
excess  of  hydrochloric  acid  in  the  solution  will  pass  through 
the  walls  of  the  bladder  into  the  water  on  the  outside  of  the 
latter.  By  renewing  the  water  in  the  pail  constantly,  there 

will  finally  remain  behind  in  the 
bladder  only  silicic  acid.  In- 
stead of  a  bladder,  a  bag  made 
of  parchment  paper  could  also 
be  used.  This  process  of  thus 
separating  the  silicic  acid  from 
the  other  ingredients  in  the 
solution  was  first  used  by 
Thomas  Graham.  It  is  called 
dialysis.  By  carefully  evapo- 
rating off  some  of  the  water, 
the  silicic  acid  solution  may  be 
concentrated  till  it  contains 
about  10  per  cent  silicic  acid.  However,  the  latter  is  very 
apt  to  separate  in  the  form  of  a  jelly  on  standing. 

Salts  of  silicic  acid  are  exceedingly  abundant  in  nature. 


FIG.  21.  —  Preparing  silicic  acid 
by  dialysis. 


BORON  AND   SILICON  79 

The  only  soluble  salts  of  this  acid  are  those  of  sodium  and 
potassium  and  these  are  prepared  artificially.  The  naturally 
occurring  silicates  are  insoluble.  Among  some  of  the  most 
important  of  these  may  be  mentioned :  potash  feldspar 
KAlSi3O8,  soda  feldspar,  NaAlSi3O8,  lime  feldspar  CaAl2Si2O8, 
kaolin  or  day  H2Al2Si2O8 . 2  H2O,  serpentine  Mg3Si2O7,  oliv- 
ine  Mg2SiO4,  meerschaum  Mg2Si3O8 . 4  H2O,  soapstone  or 
talc  Mg3H2Si4Oi2,  asbestos  Mg3Si2O7 . 2  H2O,  hornblende 
Mg2CaFeSi4Oi2,  and  mica  KH2Al3Si3Oi2.  Granitic  rocks  con- 
sist of  crystals  of  quartz,  feldspar,  and  mica.  Our  fine  clay 
soils  are  formed  by  the  disintegration  of  the  granitic  rocks, 
partly  by  the  action  of  glaciation  in  earlier  geological  ages, 
partly  by  the  process  of  weathering,  that  is,  by  the  gradual 
action  of  water,  air,  and  wind,  particularly  by  alternate 
freezing  and  thawing  of  water  in  the  crevices  of  the  rocks. 
Because  of  their  content  of  potassium  and  also  of  phos- 
phorus, for  granitic  rocks  and  the  clay  that  have  come  from 
their  disintegration  always  contain  minor  amounts  of  cal- 
cium phosphate,  clay  soils  are  in  general  quite  desirable  for 
agricultural  purposes. 

While  sand  and  the  naturally  occurring  silicates  are  all 
only  very  slightly  soluble  in  water,  yet  they  are  by  no  means 
entirely  insoluble.  So  all  terrestrial  waters  like  those  of  springs, 
wells,  rivers,  lakes,  and  the  ocean,  as  well  as  all  soil  waters, 
contain  silicates  in  solution.  From  these  dissolved  silicates, 
plants  derive  in  a  considerable  part  the  mineral  matter 
which  constitutes  the  ash  that  remains  when  they  are  in- 
cinerated. Silica  itself  is  frequently  met  in  the  ash  of  plants. 
It  is  found  particularly  in  the  ash  of  the  stalks  of  the  cereals, 
of  grasses,  of  bamboo  and  other  canes,  to  which  it  gives 
stability.  Often  half  of  the  ash  consists  of  silica.  In 
feathers,  in  the  hair  of  animals,  and  in  the  shells  of  various 
crustaceans,  silica  abounds.  About  40  per  cent  of  the  ash 


80  CHEMISTRY  AND   DAILY  LIFE 

of  the  feathers  of  birds  consists  of  silica.  Deposits  of  dia- 
tomic or  infusorial  earth  consist  of  the  siliceous  remains  of 
minute  organisms.  This  infusorial  earth  is  used  in  making 
dynamite,  which  is  essentially  nitroglycerine  mixed  with 
infusorial  earth  and  then  molded  into  sticks.  In  the  plant 
and  animal  bodies  silica  is  doubtless  combined  with  other 
elements  in  the  form  of  quite  complex  compounds.  The 
exact  nature  of  these  has  not  yet  been  determined. 

Hydrofluoric  acid  will  attack  silica,  forming  a  volatile 
compound,  silicon  tetrafluoride  and  water,  thus : 

SiO2         +          4HF  SiF4         +     2  H20 

silica  hydrofluoric  acid          silicon  tetrafluoride  water 

For  this  reason  hydrofluoric  acid  is  much  used  in  the  lab- 
oratory in  analyzing  silicates.  It  is  also  employed  in 
etching  silica,  silicates,  glass,  and  porcelain.  The  etching 
depends  upon  the  fact  that  silicon  tetrafluoride  is  formed, 
and  that  fluorides  of  any  bases  that  may  be  present  are 
simultaneously  produced.  The  art  of  thus  etching  glass 
has  been  known  for  centuries. 

QUESTIONS 

1.  What  is  borax  ?     What  use  is  made  of  it  ? 

2.  How  is  boric  acid  prepared ?     What  is  it  used  for? 

3.  What  is  the  most   abundant    compound   of   silicon?     How 
much  silicon  do  100  Ib.  of  it  contain  ? 

4.  Make  a  list  of  the  most  important  things  in  the  manufacture 
of  which  quartz  is  used. 

5.  What  is  water  glass  ?     How  is  it  made,  and  for  what  purpose 
is  it  used  ? 

6.  How   are   clay  soils  formed?    Why  are   they  desirable  for 
agricultural  purposes  ? 

7.  Discuss  the  occurrence   of  silica   in  natural  waters,   also   in 
plants  and  animals. 

8.  What  is  the  action  of  hydrofluoric  acid  upon  silicates  ? 


CHAPTER  IX 


CARBON  AND  ITS,  COMPOUNDS 

WHEN  a  porcelain  plate  is  held  in  the  flame  of  a  candle, 
carbon  deposits  on  the  plate  in  the  form  of  soot,  which  is 
also  called  lampblack.  When  in  the  process  of  baking  pota- 
toes, apples,  bread,  or  meats  they  are  left  too  long  in  a  some- 
what overheated  oven,  only  charred  masses  which  are 
largely  carbon  remain.  In  fact,  all  animal  or  vegetable  matter 
when  similarly  heated  yields  residues  of  carbon,  showing  that  the 
latter  element  is  an  essential  constituent  of  all  living  beings. 
Such  charred  remains  of  animal  or  vegetable  matter  always 
weigh  much  less  than  the  original  material,  which  is  due  to 
the  fact  that  a  large  portion  of  the  latter  has  been  volatilized 
during  the  process  of  heating.  What  remains  is  very  largely 
carbon  plus  the  mineral  constituents,  i.e  the  ash.  On 
continued  heating  in  the  air  the  carbon  in  the  charred  mass 
gradually  burns  off, 
and  there  is  finally 
left  nothing  but  the 
ash. 

By  heating  wood 
out  of  contact  with 
the  air  in  ovens 
charcoal  is  pro- 
duced. When  coal 
is  similarly  heated,  coke  is  formed;  and  when  bones  are 
thus  treated,  bone  black  results.  In  like  manner  blood 
charcoal  may  be  made  from  blood.  Charcoal  is  generally 
G  81 


FIG.  22.  —  Making  charcoal.    A  vertical  section 
through  the  center  of  a  pile. 


82 


CHEMISTRY  AND   DAILY  LIFE 


produced  by  piling  up  wood  in  a  suitable  manner,  covering 
the  whole  with  earth  to  exclude  undue  access  of  air,  and 
then  setting  fire  to  the  wood.  Thus  a  portion  of  it  burns, 
and  the  rest  is  merely  charred  because  it  is  heated  practi- 
cally out  of  contact  with  the  air.  Charcoal,  coke,  and  bone 
black  ahcays  contain,  besides  carbon,  the  mineral  substances, 
i.e.  the  ash,  of  the  original  material  that  ivas  charred. 


FIG.  23.  —  Charcoal  burning  in  Bavaria. 

Diamond  is  crystalline  carbon.  It  is  the  hardest  substance 
known.  When  pure  it  is  colorless  and  has  a  high  index  of 
refraction,  for  which  reason  it  is  greatly  prized  as  a  gem. 
Less  desirable  pieces  of  diamond  are  used  for  making  drills 
to  drill  rocks.  Graphite  also  occurs  in  nature  and  is  not 
infrequently  in  a  fairly  pure  state.  It  is  soft,  black,  and 
"  soapy  "  to  the  touch.  It  is  used  as  a  lubricant,  also  for 
making  "  lead  "  pencils.  Graphite  is  also  termed  plumbago, 


CARBON  AND   ITS  COMPOUNDS  83 

which  name  originated  because  it  was  formerly  thought  that 
the  substance  contained  lead.  Graphite  is  now  made  arti- 
ficially by  heating  carbon  very  highly  out  of  contact  with  the 
air  in  the  electric  furnace,  and  then  allowing  it  to  cool  very 
slowly.  Under  these  conditions  the  amorphous  carbon  is 
changed  to  graphite.  The  latter  may  now  be  obtained  in 
pieces  of  almost  any  size  desired.  These  can  readily  be 
worked  into  any  form  required  by  means  of  lathes,  milling 
machines,  or  bench  tools.  Much  of  this  artificial  graphite 
is  now  used  in  making  pencils,  electrodes  for  electrolytic 
work,  resistances,  etc. 

Charcoal  will  absorb  gases,  and  hence  it  is  frequently  used  to 
take  odoriferous  gases  out  of  cisterns,  pits,  vaults,  etc.  The 
cause  of  such  gases  ought  in  all  cases  to  be  removed,  however, 
if  possible.  To  hang  a  bag  full  of  charcoal  in  an  ill-smell- 
ing cistern,  when  the  latter  contains  decaying  organic 
matter  that  ought  to  be  taken  out,  is  obviously  not  the 
proper  way  of  dealing  with  the  problem.  In  the  sick  room 
charcoal  dressings  are  at  times  employed  to  absorb  fetid 
odors  issuing  from  ulcers.  Such  dressings  need  frequent 
renewal  to  be  efficient. 

Bone  black  consists  of  only  about  8  to  12  per  cent  carbon, 
the  remainder  being  largely  calcium  phosphate.  Bone  black 
absorbs  many  coloring  matters  from  solutions,  and  hence  is 
used  in  sugar  refining  to  remove  the  brown  color  from  the 
sugar  solutions.  Blood  charcoal  is  more  expensive  than 
bone  black.  It  absorbs  coloring  matter  better,  and  conse- 
quently is  often  employed  in  the  chemical  laboratory  in 
experimental  work.  Like  charcoal,  bone  black  and  blood 
charcoal  also  absorb  odors. 

Coal  represents  the  fossil  remains  of  plants  of  the  carbon- 
iferous and  other  geological  ages.  By  the  gradual  loss  of 
water  and  other  volatile  matter,  like  marsh  gas,  hydrogen, 


84  CHEMISTRY  AND   DAILY  LIFE 

etc.,  these  vegetable  remains  have  gradually  been  trans- 
formed to  coal.  Wood  fiber,  peat,  brown  coal,  soft  coal  or 
bituminous  coal,  and  anthracite  or  hard  coal  represent  a  series 
of  gradations  in  the  gradual  process  which  has  taken  place  in 
nature  in  the  production  of  coal.  Beginning  with  wood 
fiber,  by  gradual  loss  of  oxygen,  hydrogen,  and  some  carbon 
as  well,  the  other  products  just  enumerated  may  be  regarded 
as  having  been  formed.  So  anthracite  generally  consists  of 
about  95  per  cent  carbon,  the  rest  being  ash  plus  a  few  per 
cent  of  volatile  matter.  In  soft  coal  there  generally  is  about 
80  per  cent  carbon  and  a  very  much  higher  amount  of  vola- 
tile matter  than  in  hard  coal.  Soft  coal  is  consequently  used 
for  making  coal  gas  for  heating  and  illuminating  purposes. 
In  this  process  the  coal  is  heated  out  of  contact  with  the  air 
in  iron  retorts.  In  the  latter  finally  coke  remains,  which  also 
contains  the  mineral  content  or  ash  of  the  coal.  The  follow- 
ing represents  the  composition  of  a  fairly  typical  sample  of 
coal  gas :  methane  or  marsh  gas,  34.5  per  cent ;  hydrogen, 
49  per  cent;  carbon  monoxide,  7.2  per  cent;  nitrogen,  2.3 
per  cent;  oxygen,  nil;  carbon  dioxide,  1.1  per  cent;  illumi- 
nants,  benzene,  etc.,  5  per  cent.  Ammonia  is  also  always 
formed  in  the  manufacture  of  coal  gas,  as  already  stated  in 
Chapter  IV,  but  it  is  washed  out  of  the  gas  before  the  latter 
is  stored  and  admitted  to  the  gas  mains.  All  of  the  ammonia 
and  ammonium  salts  of  commerce  are  obtained  from  the  gas 
liquors. 

When  coal  gas  burns  from  an  ordinary  jet,  a  luminous 
flame  results  which  deposits  soot  on  a  plate  that  is  held  in 
it.  The  luminosity  of  the  flame  is  caused  by  the  incandescent 
particles  of  carbon  that  are  present  in  the  flame.  A  hydrogen 
flame  is  colorless,  but  can  be  made  luminous  for  a  time  by 
carefully  blowing  fine  particles  of  soot  into  it.  When  suffi- 
cient oxygen  is  supplied  to  a  coal  gas  flame,  its  luminosity 


CARBON  AND   ITS  COMPOUNDS 


85 


disappears  because  the  carbon  in  the  flame  is  all  consumed ; 
for  the  latter  reason  such  a  flame  is  hotter  than  the  lumi- 
nous one.  The  Bunsen  burner,  Fig.  24,  is  an  arrangement 
for  burning  gas  by  first  mixing  it  with  a  sufficient  amount  of 


—D 


FIG.  24.  — The  Bunsen  burner  and  its  flame. 

air  so  that  more  perfect  combustion  is  secured.  The  gas 
flows  from  the  small  orifice  0  and  air  enters  at  the  opening 
A.  In  the  tube  T  both  air  and  gas  mix  well,  and  this 
mixture  is  then  ignited  at  B,  the  upper  end  of  T.  The  gas 
burns  with  a  flame  that  has  an  inner  blue  cone  C  and  an  outer 
zone  D  which  is  non-luminous.  The  inner  zone  contains 


86  CHEMISTRY  AND  DAILY  LIFE 

unconsumed  gas,  while  in  the  outer  zone  practically  com- 
plete combustion  takes  place.  This  is  the  hottest  part  of 
the  flame.  All  gas  flames  intended  for  heating  purposes 
are  arranged  on  this  principle.  So,  for  example,  the  burners 
in  the  laboratories,  the  gas  stoves  and  ranges,  the  gasoline  heaters, 
etc.,  are  all  arranged  so  that  the  gas  is  first  well  mixed  ivith 
air  and  then  the  mixture  is  burned  from  a  jet.  In  the  case 
of  blast  lamps  air  is  blown  into  the  gas  by  pressure  from 
some  source. 

A  flame  results  only  when  a  gas  burns.  Charcoal  or  coke 
never  burn  with  a  flame,  for  in  their  production  all  gases 
were  expelled  from  them.  Charcoal  or  coke  in  burning 
become  red  hot  and  glow  till  they  are  consumed  so  that  only 
ash  remains. 

When  carbon  burns  in  the  air  or  in  oxygen  in  excess, 
carbon  dioxide  results,  thus : 

c   +  o2    =    co2 

carbon         oxygen       carbon  dioxide 

When,  however,  the  amount  of  oxygen  is  limited  and  an  excess 
of  carbon  is  present,  carbon  monoxide  is  formed,  thus : 

C     +    O       =       CO 

carbon      oxygen       carbon  monoxide 

Carbon  monoxide  is  a  gas  which  burns  with  a  blue  flame, 
yielding  carbon  dioxide,  thus  : 

CO          +    O      =       CO2 

carbon  monoxide        oxygen        carbon  dioxide 

Carbon  monoxide  is  poisonous.  When  breathed  it  unites  with 
the  hemoglobin  of  the  blood  and  produces  death.  Carbon 
monoxide  is  the  most  dangerous  ingredient  of  coal  gas.  Its 
flame  is  quite  hot.  In  "  water  gas,"  which  is  a  mixture  of 


CARBON  AND   ITS   COMPOUNDS  87 

hydrogen  and  carbon  monoxide  produced  by  passing  steam  over 
white-hot  coke,  thus : 

C    +    H2O    =   CO   +   H2, 

carton  water  water  gas 

we  have  then  a  gas  which  is  excellent  for  heating,  but  not  at 
all  suitable  for  illuminating  purposes.  By  "  enriching  " 
this  gas  with  benzene,  or  gas  pro- 
duced from  petroleum  oils,  it  may 
be  used  as  illuminating  gas.  With 
the  Welsbach  mantle  lamp  water 
gas  may  be  used  very  well,  for 
here  a  non-luminous  Bunsen 
flame  is  employed,  over  which 
the  mantle,  consisting  of  a  net- 
work of  1  per  cent  cerium  oxide 
and  99  per  cent  thorium  oxide, 
is  placed.  This  "  stocking "  is 
heated  to  incandescence  and 
emits  a  brilliant  light.  Producer 
gas  consists  of  28  to  30  per  cent 
carbon  monoxide,  63  per  cent  ni- 
trogen, and  minor  amounts  of 
carbon  dioxide.  It  is  made  by 
passing  air  over  red-hot  coke. 
The  gas  is  readily  made  and  is 

FIG.  25.  — A  Welsbach  mantle. 

frequently  used  as  a   source  of 

heat  in  industrial  processes.     The  nitrogen  it  contains  is,  of 

course,  a  drawback,  for  it  acts  simply  to  dilute  the  carbon 

monoxide. 

Carbon  dioxide,  as  already  stated,  is  contained  in  the 
atmosphere,  and  from  this  source  the  carbon  that  is  found 
in  living  beings  is  really  obtained.  In  the  green  leaf  of  the 
plant  in  the  sunlight  carbon  dioxide  from  the  air  and  moisture 


88  CHEMISTRY  AND   DAILY  LIFE 

react  with  each  other,  forming  starch  and  eliminating  oxygen, 
thus :  6  C02  +  5  H20  =  6  02  +  C6H1005 

carbon  dioxide  water  oxygen  starch 

Starch  is  an  article  of  food.  It  is  present  in  large  quantities 
in  all  cereals,  potatoes,  and  other  vegetables.  As  these  are 
eaten  the  starch  is  changed  to  sugar  in  the  alimentary  canal, 
passes  through  the  walls  of  the  latter  into  the  blood,  and  is 
utilized  in  building  up  tissues  of  the  body.  The  latter  as 
we  live  are  again  continually  slowly  oxidized  by  the  oxygen 
which  passes  through  the  walls  of  the  lungs  into  the  blood 
as  we  breathe.  Thus  carbon  dioxide  is  formed  and  this  is 
exhaled  with  every  breath.  In  this  way  carbon  is  returned  to 
the  air  in  the  form  of  carbon  dioxide  and  the  carbon  cycle 
has  been  completed.  The  plant  can  now  again  take  up  the 
carbon  dioxide  and  transform  it  into  starch.  The  latter 
can  again  be  eaten,  assimilated,  oxidized  to  carbon  dioxide 
in  the  body,  and  exhaled,  and  so  on.  The  energy  that  keeps 
this  process  going  obviously  comes  from  the  sun  without  whose 
light  and  warmth  the  plant  could  not  live  and  continue  its  work 
of  transforming  carbon  dioxide  and  water  into  starch  and 
oxygen. 

Carbonated  waters  are  waters  charged  with  carbon  dioxide, 
the  latter  gas  being  placed  under  pressure  over  water  in  a 
closed  tank.  When  such  pressure  is  released  from  the  water, 
a  considerable  amount  of  the  gas  escapes  in  bubbles.  Nat- 
ural springs  whose  waters  are  charged  with  carbon  dioxide  occur 
in  nature.  So,  for  example,  at  Colorado  Springs  the  waters 
are  highly  carbonated.  Soda  water  is  water  charged  with 
carbon  dioxide.  It  is  so  called  because  the  gas  employed  was 
formerly  made  by  the  action  of  an  acid  on  baking  soda,  thus  : 

2  NaHCO3   +    H2S04      =    Na2SO4     +    H2O  +  2  CO2 

baking  soda       sulphuric  acid      sodium  sulphate        water     carbon  dioxide 


CARBON   AND   ITS  COMPOUNDS  89 

Carbonated  waters  are  refreshing  to  the  taste  and  are  conse- 
quently rightfully  highly  esteemed.  Carbon  dioxide  from  the 
fermentation  industries  is  now  commonly  stored  in  steel  cyl- 
inders and  used  for  making  carbonated  beverages  of  all 
kinds.  Since  carbon  dioxide  occurs  in  the  air  and  since 
water  dissolves  carbon  dioxide,  the  latter  is  present  in  all 
natural  waters. 

Carbonates  are  salts  of  carbonic  acid.  Carbon  dioxide  is 
really  carbonic  acid  anhydride,  that  is,  carbonic  acid  minus 
water.  Carbonic  acid  is  H2CO3,  but  it  has  never  been  isolated, 
for  it  decomposes  readily  into  carbon  dioxide  and  water,  thus  : 

H2C03     =      C02      +     H20 

carbonic  acid      carbon  dioxide         water 

The  salts  of  carbonic  acid  are,  however,  quite  common  and 
stable  under  ordinary  conditions.  They  are  also  of  great  im- 
portance. So  limestone  and  marble  consist  of  almost  pure 
calcium  carbonate,  CaCO3.  Magnesium  limestone  or  dolo- 
mite consists  of  magnesium  and  calcium  carbonate,  MgCOs 
-f-  CaCO3.  These  are  valuable  as  building  materials,  (1)  as 
building  stones  and  (2)  for  making  building  lime.  In  the 
process  of  making  lime  the  limestone  is  heated  in  a  kiln 
out  of  contact  with  the  air.  Thus  carbon  dioxide  is  expelled, 
and  lime,  calcium  oxide,  CaO,  remains  : 

CaCO3  on  heating     =     CaO         -f          CO2 

calcium  carbonate  calcium  oxide          carbon  dioxide 

limestone  lime 

In  slaking  the  lime,  as  for  building  purposes,  making  white- 
wash for  walls,  or  producing  liquids  for  spraying  trees,  etc. 
calcium  hydroxide  results  and  considerable  amounts  of  heat 
are  evolved  as  the  chemical  union  of  lime  and  water  proceeds, 

thus:  CaO      +    H20      =      Ca(OH)2 

calcium  oxide          water  calcium  hydroxide 

lime  or  slaked  lime 


90  CHEMISTRY  AND   DAILY  LIFE 

When  this  slaked  lime  is  mixed  with  sand,  mortar  is  obtained, 
whose  hardening  or  "  setting  "  proceeds  because  water  dries  out 


FIG.  26.  —  A  homemade  lime  kiln. 

and  at  the  same  time  the  carbon  dioxide  of  the  air  again  acts  on 
the  slaked  lime,  forming  calcium  carbonate  again,  thus  : 

Ca(OH)2     +         C02       =         CaC03      +     H2O 

calcium  hydroxide       carbon  dioxide      calcium  carbonate         water 
slaked  lime 

The  crystals  of  calcium  carbonate  tightly  hold  the  grains  of 
sharp  sand  in  place,  thus  forming  a  solid  mass.  It  is'  clear 
that  in  order  to  set  well,  lime  mortar  must  haw  plenty  of  air 
so  that  it  may  secure  the  necessary  carbon  dioxide  therefrom. 
Moreover,  the  air  should  be  fairly  dry  in  order  that  the  water 
may  dry  out  of  the  mortar.  Plastering  and  bricklaying  in 
cold,  damp  weather  does  not  produce  the  best  results. 


CARBON  AND   ITS   COMPOUNDS  91 

In  many  sands  and  soils  grains  of  limestone,  calcium  car- 
bonate, are  found.  The  shells  of  oysters,  clams,  and  other  shell- 
fish consist  largely  of  calcium  carbonate.  Indeed,  it  is  quite 
probable  that  the  large  beds  of  limestone  and  marble  (which 
is  merely  a  purer  form  of  limestone)  have  been  formed  from 
the  remains  of  mollusks,  whose  shells  have  been  deposited 
from  the  sea  in  deep  layers  which  have  later,  under  heat  and 
pressure,  been  transformed  to  the  crystalline  state. 

Carbon  is  further  found  in  nature  in  petroleum,  a  liquid 
which  consists  of  a  mixture  of  compounds  of  carbon  and  hydro- 
gen. Compounds  of  the  latter  elements  are  called  hydro- 
carbons. It  is  not  easy  to  separate  from  petroleum  in  pure 
form  any  one  of  the  mixture  of  hydrocarbons  of  which  it 
consists.  However,  it  is  not  at  all  difficult  to  separate  petro- 
leum into  groups  of  hydrocarbons  whose  boiling  points  are 
fairly  close  together.  This  is  actually  done  in  practice  by  the 
process  of  fractional  distillation.  Petroleum  is  distilled,  and 
separate  portions  passing  over  between  certain  temperatures  are 
collected  in  different  receivers.  In  this  way  there  are  obtained 
from  petroleum  :  rhigolene,  which  boils  at  about  room  tem- 
perature ;  petroleum  ether,  boiling  between  50°  and  60°  C. ; 
gasoline,  boiling  between  70°  and  90°  C. ;  naphtha,  boiling 
from  about  90°  to  120°  C. ;  benzine,  boiling  from  110°  to  140° 
C. ;  and  kerosene,  boiling  between  150°  and  300°  C.  Above 
the  latter  temperature  heavy  oil  passes  over  as  the  distilla- 
tion proceeds.  This  is  used  for  lubricating  purposes.  After 
the  lubricating  oils  have  been  distilled  off,  vaseline  passes 
over,  and  finally  paraffine  is  prepared  from  the  residue  that 
remains  in  the  retort.  The  oils  prepared  from  petroleum  are 
often  called  mineral  oils  to  distinguish  them  from  the  fats  and  oils 
of  plant  or  animal  origin.  The  fats  and  oils  from  the  latter 
sources  are  not  hydrocarbons.  They  are  compounds  of  car- 
bon, hydrogen,  and  oxygen.  For  the  most  part  they  are 


92  CHEMISTRY  AND   DAILY  LIFE 

salts  in  which  glycerine  is  the  base  and  oleic,  palmitic,  and 
stearic  acids  are  the  acids.  By  heating  such  fats  with  strong 
bases  like  caustic  potash  or  caustic  soda  glycerine  is  set  free, 
and  the  sodium  salt  of  the  fatty  acid,  a  soap,  is  formed.  So 
for  example : 

(C17H33COO)3C3H5    +    3NaOH   =   3  C17H33COONa 

glycerine  oleate  caustic  soda  sodium  oleate 

cottonseed  oil  castile  soap* 

+  C3H6(OH)3 

glycerine 

Mineral  fats  and  oils  are  hydrocarbons  and  consequently  can- 
not be  transformed  into  soaps  by  boiling  with  lye.  It  is  thus 
easy  to  distinguish  between  mineral  oils  and  those  of  plant  or 
animal  origin. 

Petroleum  products  cannot  serve  as  foods.  There  is  no  hy- 
drocarbon which  can  be  used  for  food.  The  lower  boiling 
hydrocarbon  oils  from  petroleum  are  used  as  fuels,  for  heating, 
and  for  propelling  internal  combustion  engines.  When  com- 
pletely burned  they  form  carbon  dioxide  and  water.  Hy- 
drogen burns  more  readily  than  carbon,  and  the  richer  in 
hydrogen  a  hydrocarbon  is,  the  more  volatile  it  is  and  the  more 
readily  it  burns.  For  these  reasons  petroleum  ether,  gasoline, 
naphtha,  and  benzine  are  more  suitable  than  kerosene  for  running 
so-called  gasoline  engines,  although  kerosene  is  used  at  present 
with  a  fair  degree  of  success,  especially  in  those  engines  in 
which  that  hydrocarbon  is  transformed  into  a  very  fine  mist 
by  mechanical  means.  This  mist  when  mixed  with  air  and 
subjected  to  the  action  of  the  electric  spark  in  the  engine 
cylinder  explodes  fairly  readily.  It  should  be  remembered 
that  all  gases  which  burn  in  the  air  will  also  form  mixtures 
with  air  which  are  explosive  when  ignited.  Upon  this  fact 
the  running  of  gas  and  gasoline  engines  depends.  The  fuel 
is  in  each  case  volatilized  and  mixed  with  air,  and  the  mix- 


CARBON  AND   ITS  COMPOUNDS  93 

ture  is  then  exploded  in  the  cylinder  of  the  engine  by 
ignition. 

Acetylene  is  another  hydrocarbon  which  has  come  into 
prominent  use,  particularly  for  lighting  purposes.  It  is  a 
gas  at  ordinary  temperatures  and  is  readily  prepared  by  the 
action  of  calcium  carbide,  a  stonelike  solid,  upon  water, 

CaC2     +    2  H2O  =  C2H2     +      Ca(OH)2 

calcium  carbide        water         acetylene         calcium  hydroxide 

slaked  lime 

The  calcium  carbide  is  obtained  by  heating  lime  and  coke 
together  in  the  electric  furnace  out  of  contact  with  the  air,  thus  : 

CaO    +   3C  CaC2          +  CO 

lime  coke  calcium  carbide        carbon  monoxide  gas 

On  account  of  its  high  carbon  content,  acetylene  has  great 
illuminating  power  and  is  consequently  frequently  used  for 
lighting  purposes,  especially  on  automobiles,  in  running 
projection  lanterns,  etc. 

From  petroleum  oils,  too,  gas  of  high  illuminating  power 
may  be  obtained  by  "  cracking  "  the  oils,  which  consists  of 
having  them  come  into  contact  with  red-hot  stone  surfaces 
out  of  contact  with  the  air.  These  oil  gases  are  now  produced 
in  many  municipal  gas  plants.  They  are  also  put  on  the 
market  compressed  in  steel  cylinders.  Pintsch  gas,  which 
is  used  for  lighting  railway  cars,  is  a  rich  oil  gas  of  this  char- 
acter. Blaugas,  named  from  its  inventor  Blau,  is  also  a  sim- 
ilar oil  gas. 

Hydrocarbons  are  wry  numerous  and  they  may  be  regarded 
as  the  mother  substances  from  which  all  other  compounds  of 
carbon  are  derived.  The  simplest  hydrocarbon  is  methane, 
or  marsh  gas,  CH4.  It  is  called  marsh  gas  because  it  issues 
from  the  marshes  on  warm  summer  days  as  the  vegetable 
matter  which  is  always  present  on  the  bottom  of  such  waters 


94 


CHEMISTRY  AND   DAILY  LIFE 


slowly  decays.     The  gas  may  also  be  prepared  artificially, 
by  heating  sodium  acetate  with  a  caustic  alkali,  thus  : 

CH3COONa     +        NaOH        =     Na2CO3      +     CH4 

sodium  acetate  sodium  hydroxide      sodium  carbonate       methane 


Marsh  gas  will  burn  in  the  air,  thus  : 
CH4     +  202      =        C02 

marsh  gas         oxygen  carbon  dioxide 

Mixed  with  air  it  forms  an  explosive  gas  mixture,  which  could 
be  used  for  running  an  internal  combustion  engine. 


2H20 

water 


FIG.  27.  —  Collecting  marsh  gas  from  the  bottom  of  a  ditch. 

From  marsh  gas  a  variety  of  products  may  be  obtained. 
Thus  by  treatment  with  chlorine  there  may  be  obtained 


CARBON   AND   ITS  COMPOUNDS  95 

successively,    methyl    chloride    CH3C1,    methylene   chloride 
CH2C12,  chloroform  CHC13,  and  carbon  tetrachloride   CC14, 

viz*  : 


CH4- 

hd2  = 

HC1- 

f-  CH3C1 

CHgCl  - 

hd2  = 

HC1  - 

f-  CH2C12 

CH2C12  H 

-C12  = 

HC1- 

h  CHC13 

CHC13  H 

-  C12  = 

HCH 

hCC!4 

Of  these  compounds  chloroform  and  carbon  tetrachloride  are 
by  far  the  most  important  ones.  Both  are  liquids  at  ordi- 
nary temperatures.  Chloroform  boils  at  61°  C.,  is  heavier 
than  water,  has  a  rather  agreeable  odor,  and  is  used  as  an  anaes- 
thetic. The  analogous  iodine  compound,  iodoform,  CHI3, 
is  a  yellow  crystalline  solid  of  rather  disagreeable  odor.  It  is 
used  in  surgery  as  a  dressing  for  wounds,  especially  when 
pus  has  formed.  Carbon  tetrachloride  is  also  a  colorless,  heavy 
liquid  which  does  not  dissolve  in  water.  It  boils  at  76  °  and  it  is 
not  inflammable,  which,  of  course,  is  to  be  expected,  consider- 
ing that  it  consists  of  carbon  and  chlorine.  Carbon  tetra- 
chloride is  an  excellent  solvent  for  fats,  and  hence  is  often  used 
for  removing  grease  spots  from  clothes,  for  which  purpose  it  is 
to  be  recommended,  for.it  does  not  form  dangerous  explosive 
mixtures  with  the  air  like  gasoline,  for  example,  which  is  also 
used  in  cleaning  clothes.  However,  carbon  tetrachloride  is 
much  more  expensive  than  gasoline.  The  trade  name  "carbon- 
eum  "  is  sometimes  given  to  carbon  tetrachloride.  The  latter 
compound  is  also  used  in  fire  extinguishers  of  various  forms  ,  par- 
ticularly those  of  the  syringe  type,  which  are  often  sold  at  exor- 
bitant prices.  Carbon  tetrachloride  extinguishes  fires  because 
it  evaporates  and  crowds  the  air  away  from  the  burning  sub- 
stances, thus  making  it  impossible  for  combustion  to  proceed 
further.  During  the  evaporation  of  the  carbon  tetrachloride 
heat  is  absorbed,  and  so  the  temperature  of  the  burning 
substances  is  lowered  and  this  also  tends  to  check  the  fire. 


96 


CHEMISTRY  AND   DAILY  LIFE 


Fires  may  be  extinguished  in  the  following  ways :  (I)  by  cutting 
off  the  supply  of  air  from  the  burning  materials,  (2)  by  lowering 
the  temperature  of  the  materials  on  fire  so  that  further  combustion 
is  impossible.  Now  when  water  is  thrown  upon  an  ordinary 
fire  the  latter  is  extinguished  for  two  reasons;  namely,  (1) 
the  water  lowers  the  temperature,  and  (2)  it  also  forms  clouds  of 
water  vapor  which  crowd  the  air  way.  It  is  obvious  that  when 
oils,,  which  will  float  on  w.ater,  are  burning,  the  addition  of 
water  cannot  prevent  access  of  air  to  such  a  fire,  for  the  oils 
will  come  on  top  of  the  water  and  continue  to  burn,  the  water 
serving  rather  as  a  means  of  spreading  the  burning  oil. 
Many  incipient  fires  can  be  put  out  by  covering  them  with 
blankets,  rugs,  earth,  etc.,  and  thus  shutting  off  the  air.  Burn- 
ing oils  are  extinguished  by  means  of  carbon  dioxide  and  carbon 
tetrachloride.  Still  other  chemicals  have 
been  suggested  for  this  purpose,  but  they 
have  not  come  into  common  use.  Carbon 
dioxide  is  one  of  the  very  best  means  known 
for  putting  out  small  fires.  It  may  be 
delivered  from  cylinders  containing  com- 
pressed carbon  dioxide,  or  may  be  gener- 
ated by  the  action  of  sulphuric  acid  upon 
a  saturated  solution  of  baking  soda,  sodium 
bicarbonate,  NaHCO3.  The  fire  extinguish- 
ers that  are  to  be  inverted  and  are  then 
ready  for  use,  Fig.  28,  contain  a  solution 
of  sodium  bicarbonate  and  a  glass  bottle 
in  which  sulphuric  acid  has  been  placed. 
This  bottle  is  loosely  stoppered  with  a 
lead  stopper.  On  inverting  the  entire  appa- 
ratus the  sulphuric  acid  bottle  is  inverted,  its  stopper  drops 
out,  the  acid  mingles  with  the  sodium  bicarbonate  solution, 
carbon  dioxide  is  generated,  and  the  pressure  that  thus  results 


FIG.  28. — A  fire  ex- 
tinguisher partly 
opened  to  show  its 
construction. 


CARBON  AND  ITS  COMPOUNDS  97 

is  sufficient  to  cause  a  stream  of  the  saturated  effervescing 
solution  to  be  delivered  from  the  nozzle.  This  directed  upon 
the  base  of  the  flames  cools  the  burning  material  and  at  the 
same  time  the  carbon  dioxide  liberated  crowds  the  air  away 
and  thus  extinguishes  the  fire.  It  need  hardly  be  stated 
that  small  fires  should  be  promptly  put  out,  and  the  means 
for  doing  so  should  be  on  hand  wherever  there  is  special 
danger.  Large  conflagrations  are  at  times  well-nigh  impos- 
sible to  cope  with  because  of  the  mass  of  water  that  would 
be  required  to  prevent  access  of  air  and  to  lower  the  high 


FIG.  29.  — A  fire  extinguisher  in  action. 

temperatures  below  the  kindling  point.  In  such  cases  the 
best  that  can  be  done  is  to  prevent  the  spread  of  the  fire 
by  removal  of  combustible  material  to  which  there  is  imme- 
diate danger  that  the  flames  will  spread. 

When  methyl  chloride,  CH3C1,  is  treated  with  caustic  soda, 
common  salt  splits  off  and  simultaneously  methyl  hydroxide, 
also  called  methyl  alcohol  or  spirits  of  wood,  is  formed,  thus  : 

CH3C1        +       NaOH     =     NaCl      +     CH3OH 

methyl  chloride  caustic  soda        common  salt         wood  alcohol 

H 


98  CHEMISTRY  AND   DAILY  LIFE 

Methyl  alcohol  is  called  wood  alcohol  because  it  is  commer- 
cially produced  by  the  dry  distillation  of  wood,  that  is  to  say 
by  heating  wood  out  of  contact  with  the  air,  in  which  process 
a  variety  of  other  products  like  pyroligneous  acetic  acid, 
creosote,  etc.,  are  also  formed.  Methyl  alcohol  is  poisonous. 
It  is  used  for  fuel  and  for  making  various  chemical  substances. 
So,  for  instance,  upon  oxidation  of  methyl  alcohol  formalde- 
hyde is  obtained,  thus : 

CH3OH  +    O     =     HCOH     +  H20 

methyl  oxygen        formaldehyde         water 

alcohol 

Formaldehyde  is  a  pungent,  poisonous  gas  which  is  soluble  in 
water.  Its  If)  per  cent  solutions  are  sold  on  the  market  as 
formaline.  It  serves  as  an  antiseptic  in  fumigating  rooms, 
and  its  solutions  serve  in  treating  seeds  to  free  them  from 
injurious  fungi,  etc.,  before  planting.  So,  for  example,  po- 
tatoes that  are  infested  with  potato  scab  are  advantageously 
treated  with  formaldehyde  solution  before  planting.  The  use 
of  formaldehyde  as  a  preservative  in  milk  and  other  foods 
and  drinks  is  forbidden  by  law  because  the  substance  is 
poisonous. 

On  further  oxidation  of  formic  aldehyde,  formic  acid,  a 
fairly  powerful  acid,  may  be  obtained,  thus : 

HCOH     +    O     =   HCOOH 

formaldehyde        oxygen         formic  acid 

But  one  of  the  hydrogens  of  this  acid  is  replacable  by  metals, 
and  when  this  has  been  accomplished  the  resulting  salts  are 
the  formates.  Formic  acid  was  formerly  made  by  the  dis- 
tillation of  red  ants,  in  which  it  occurs. 

Ordinary  alcohol,  also  called  grain  alcohol  or  spirits  of  wine, 
is  made  commercially  by  the  fermentation  of  sugar  by  means 


CARBON  AND   ITS  COMPOUNDS 


99 


of  yeast.     As  the  yeast  plant,  Fig.  30,  lives  it  produces  carbon 
dioxide  from  the  sugar,  thus : 


grape  sugar 


yeast     =     2  CO2 

carbon  dioxide 


2  C2H5OH 

alcohol 


FIG.  30. —Yeast  cells. 


Like  wood  alcohol,  grain  alcohol  may  serve  as  a  fuel.  Both 
substances  burn  with  a  hot,  blue  flame,  forming  carbon  dioxide 
and  water.  On  careful  oxidation  ordinary  alcohol  forms  first 
acetic  aldehyde  and  then  acetic  acid,  thus  : 


CH3  .  CH2  .  OH 

ordinary  alcohol 

+   o    = 

CHaCOH     -f 

acetic  aldehyde 

H2O 

water 

CHaCOH 

acetic  aldehyde 

+  o   = 

oxygen 

CHaCOOH 

acetic  acid 

The  oxidation  of  alcohol  to  acetic  acid  is  accomplished  com- 
mercially by  means  of  an  organism  called  mother  of  vinegar. 
The  dilute  alcohol  is  allowed  to  trickle  over  beech  wood 
shavings  contained  in  a  vat,  and  in  the  presence  of  air  and  the 
acetic  acid  organism  the  alcohol  is  oxidized  to  vinegar. 
The  latter  is  a  solution  of  about  4  per  cent  acetic  acid.  From 


100  CHEMISTRY  AND   DAILY  LIFE 

this  by  the  action  of  bases  a  series  of  salts  called  acetates  is 
formed.  Of  the  metallic  acetates  lead  acetate,  Pb(CH3CO2)2, 
is  perhaps  the  most  common  in  practice,  though  sodium  ace- 
tate, Na  .  CH3CO2,  and  copper  acetate,  Cu(CH3CO2)2,  are  also 


FIG.  31.  —  Making  vinegar  by  the  quick  vinegar  process. 

often  used.  The  latter,  it  will  be  recalled,  forms  Paris  green 
when  united  with  copper  arsenite.  Vinegar  is  also  formed  by 
the  fermentation  of  sugar  and  subsequent  oxidation  of  the  result- 
ing alcohol  in  fruit  juices,  like  cider,  for  example.  By  adding 
to  cider  an  antiseptic  like  boric  acid,  benzoic  acid,  or  sodium 
benzoate,  fermentation  may  be  prevented,  but  as  these 
substances  are  deleterious  to  health,  the  practice  is  not  to  be 
recommended.  Cider  or  grape  juice  may  be  kept  unfermented 


CARBON  AND  ITS  COMFOT^SS  \      ^^ 

if  it  is  carefully  heated  to  destroy  the  microorganisms  it  con- 
tains, and  then,  while  still  hot,  sealed  in  air-tight  bottles. 

Denatured  alcohol  is  grain  alcohol  which  has  been  rendered 
unfit  for  drinking  purposes  by  adding  about  10  per  cent  of 
wood  alcohol,  pyridine,  C5H5N,  or  other  poisonous  liquid. 
Denatured  alcohol  is  sold  duty-free  and  is  used  as  a  fuel  and  for 
manufacturing  purposes. 

Whiskeys  and  rum  contain  from  45  to  65  per  cent 
of  alcohol,  wines  from  8  to  20  per  cent,  and  beers  from 
3  to  5  per  cent.  As  beverages,  alcoholic  liquids  are  now 
recognized  as  neither  necessary  nor  desirable  for  the  best  of 
health. 

There  are  many  other  alcohols  besides  wood  alcohol  and  grain 
alcohol;  however  but  few  of  them  are  in  common  use.  Glyc- 
erine is  really  an  alcohol.  Its  composition  is  expressed  by 
the  formula  C3H5(OH)3.  All  alcohols  contain  the  OH  group. 
They  may  all  act  as  bases,  reacting  with  acids  to  form  salts  and 
water.  So,  for  instance, 

C2H5OH     +    CH3COOH    =   CH3COOC2H5     +     H2O 

alcohol  acetic  acid  ethyl  acetate  water 

It  will  be  seen  at  once  that  this  reaction  is  similar  to  that  when 
sodium  hydroxide  acts  on  acetic  acid  : 

NaOH     +     CH3COOH  =  CH3COONa  +  H2O 

sodium  hydroxide  acetic  acid  sodium  acetate  water 

Salts,  like  ethyl  acetate,  in  which  there  is  a  hydrocarbon 
radical  which  plays  the  role  of  a  metal  in  that  it  has  basic 
properties,  are  called  ethereal  salts  or  esters.  Esters  are 
quite  common  in  nature.  So,  for  example,  wintergreen  oil, 
methyl  salicylate,  is  a  salt  of  salicylic  acid,  in  which  methyl, 
CH3,  the  radical  from  wood  alcohol,  acts  as  a  base.  Banana 
oil,  amyl  acetate,  CH3COO  .  C5Hn,  is  formed  when  acetic  acid 


CHEMISTRY  AND   DAILY  LIFE 

and  amyl  alcohol  react  with  each  other,  thus  : 
CH3COOH     +     C5HUOH    =    CH3COOC6Hii     +     H2O 

acetic  acid  amyl  alcohol  amyl  acetate  water 

The  fats  are  salts  in  which  stearic,  palmitic,  and  oleic  acids  act 
as  acids  and  glycerine  acts  as  the  base.  So  in  mutton  tallow 
we  have  principally  glycerine  stearate,  in  palm  oil  chiefly 
glycerine  palmitate,  while  hog's  lard,  cotton  seed  and  olive 
•oils  are  rich  in  glycerine  oleate.  In  general  the  fats  are  mixtures 
of  these  three  salts  of  glycerine.  The  softer  the  fat,  the  richer 
it  is  in  oleine  or  glycerine  oleate;  the  harder  the  fats,  the 
richer  they  are  in  stearine  or  glycerine  stearate.  On  heating 
the  fats  with  caustic  soda  or  caustic  potash  the  corresponding 
salts  of  sodium  or  potassium  are  formed  and  glycerine  is 
simultaneously  produced.  These  sodium  salts  of  stearic, 
palmitic,  and  oleic  acids  are  the  hard  soaps.  The  corre- 
sponding potassium  salts  are  the  soft  soaps.  Glycerine  is  a 
product  of  the  process  of  saponification  of  fats,  for  example  : 


(C17H35COO)3C3H5+3  NaOH=3  Ci7Ht6COONa-f  ej 

glycerine  caustic  soda          sodium  stearate  glycerine 

stearate  lye  hard  soap 

When  used  in  hard  water,  soaps  form  an  insoluble  curdy  mass. 
This  is  really  the  calcium  soap.  Hard  water  contains  cal- 
cium salts  which  react  with  soap,  forming  the  insoluble 
calcium  soap  and  a  soluble  sodium  salt,  thus  : 

2  CnHsfiCOONa  +  CaSO4    =    (Ci7H35COO)2Ca   +   Na2S04 

sodium  stearate       calcium  sulphate        calcium  stearate     sodium  sulphate 

When  hard  water  is  first  treated  with  washing  soda,  Na2CO3,  it 
may  be  "  cleansed  "  ;  that  is  to  say,  the  calcium  may  be  pre- 
cipitated in  the  form  of  an  insoluble  compound,  calcium 
carbonate,  CaCO3,  and  then  the  water  will  not  form  a  calcium 
soap  when  treated  with  ordinary  soap.  So,  for  example  : 

CaSO4       +       Na2CO3     =      Na2SO4        +    'CaC03 

calcium  sulphate      sodium  carbonate    sodium  sulphate     calcium  carbonate 


CARBON  AND  ITS  COMPOUNDS  103 

Instead  of  washing  soda,  borax  may  also  be  employed  to  soften 
the  water,  in  which  case  calcium  borate  is  precipitated.  Am- 
monium carbonate  may  also  serve  for  the  same  purpose. 
It  is  best,  however,  to  use  rain  water  or  distilled  water  for  washing 
purposes  and  so  avoid  the  use  of  soda,  etc.,  for  the  process  of 
cleansing  water  is  always  expensive,  and  the  salts  that  remain 
in  the  water  are  hard  on  the  clothes  and  also  on  the  hands  of  the 
laundry  workers. 

Ether  is  made  by  very  carefully  conducting  alcohol  into 
concentrated  sulphuric  acid  heated  to  about  140°  C.  Under 
these  conditions  alcohol  loses  water,  which  is  taken  up  by  the 
sulphuric  acid,  thus : 

2C2H5OH     +     H2S04      =     H2S04.H2O     +      (C2H5)2O 

alcohol  sulphuric  acid  sulphuric  acid  ether 

hydrate 

Ether  is  the  oxide  of  ethyl,  whereas  alcohol,  it  will  be  recalled,  is 
the  hydroxide  of  ethyl.  Ether  boils  at  35°  C.  and  has  a  specific 
gravity  of  0.736.  It  is  very  inflammable.  In  this  respect 
it  is  even  more  dangerous  than  gasoline.  Ether  is  used  in 
medicine  as  an  ancesthetic.  It  is  also  employed  as  a  solvent 
for  fats  and  oils,  especially  in  analytical  chemistry.  Sulphur 
ethers  contain  sulphur  where  ordinary  ethers  contain  oxygen. 
Sulphur  ethers  have  extremely  nauseating  odors. 

Carbolic  acid  or  phenol,  C6H5OH,  is  really  not  an  organic 
acid  at  all.  It  is  an  hydroxide  derived  from  benzene,  C6H6, 
a  hydrocarbon  present  in  the  light  oil  obtained  by  distilling  coal 
tar  produced  in  the  gas  works.  In  reality,  then,  carbolic 
acid  is  closely  related  to  alcohols,  but  since  its  hydroxyl 
hydrogen  is  easily  replaced  by  metals  forming  so-called 
phenolates,  phenol  is  commonly  called  carbolic  acid.  It  is  a 
solid  whose  crystals  melt  at  42°  C.  It  turns  pink  on  exposure 
to  air.  It  is  poisonous  and  corrosive  to  the  skin.  Fifteen  parts 
of  cold  water  dissolve  about  1  part  of  phenol,  and  the  solu- 


104  CHEMISTRY  AND   DAILY  LIFE 

tion  serves  as  an  antiseptic.  Phenol  has  a  very  characteristic 
odor.  Creosote  is  a  mixture  of  guajacol,  C6H4(OCH3)OH, 
and  creosol,  C6H3(CH3)(OCH3)OH,  produced  when  wood  is 
heated  with  but  limited  access  of  air,  as  in  smoking  fish,  hams, 
bacon,  etc.  These  phenols  penetrate  into  the  meats  and  so 
preserve  them  from  the  ravages  of  microorganisms,  thus 
preventing  putrefaction.  Hydrochinone,  C6H4(OH)2,  and 
pyrogallol,  C6H3(OH)3,  also  called  pyrogallic  acid,  are  also 
phenols.  They  are  used  as  developers  in  photography. 

From  the  hydrocarbon  benzene,  C6H6,  are  derived  many 
other  useful  substances,  such  as  aniline  C6H5NH2,  nitroben- 
zene or  oil  of  mirbane,  C6H5NO2,  benzoic  acid  C6H5COOH, 
whose  sodium  salt,  sodium  benzoate  C6H5COONa,  has  been 
used  as  a  preservative  for  foods.  Practically  all  the  dye- 
stuffs  that  are  now  used  for  dyeing  fabrics  of  all  kinds  are 
derivatives  of  benzene,  CeHe.  They  are  consequently  often 
spoken  of  as  coal  tar  dyes,  aniline  dyes,  or  coal  tar  coloring 
matters.  They  are  excellent,  and  have  practically  completely 
replaced  vegetable  coloring  matters  in  the  arts. 

Among  the  many  other  organic  acids  that  exist  there  are 
the  following,  which  are  frequently  met  in  daily  life :  (1) 
oxalic  acid  (COOH)2,  which  is  made  from  sawdust  by  oxi- 
dizing the  latter  with  the  aid  of  nitric  acid.  It  serves  for  re- 
moving ink  and  rust  spots  from  floors  and  fabrics,  and  is  fre- 
quently used  as  a  reducing  agent  in  the  laboratory.  (2)  Lac- 
tic acid,  which  occurs  in  sour  milk.  It  has  the  formula 
C2H4(OH) .  COOH.  With  bases  it  forms  lactates.  It  is  used 
with  baking  soda  in  making  biscuits,  pancakes,  etc.  Its  silver 
salt  is  used  as  an  antiseptic  in  medicine.  (3)  Malic  acid, 
CH2COOH  .  CH  .  OH  .  COOH  occurs  in  sour  apples,  in 
mountain  ash  berries,  and  in  many  other  fruits.  (4)  Tar- 
taric  acid  (CH  .  OH  .  COOH)2  occurs  in  grapes.  Its  acid 
potassium  salt  (CH  .  OH .  COOH)(CH  .  OH .  COOK)  is  cream 


CARBON  AND   ITS   COMPOUNDS  105 

of  tartar  and  is  used  in  baking  powders.  (5)  Citric  acid 
(CH2COOH)2 .  CH  .  OHCOOH  occurs  in  lemons  and  other 
citrus  fruits.  (6)  Butyric  acid,  C3H7COOH,  is  contained  in 
rancid  butter  and  gives  to  the  latter  its  disagreeable  odor. 
(7)  Valeric  acid,  C4H9COOH,  is  contained  in  the  catnip  plant, 
and  it  is  the  odor  of  this  acid  that  is  so  much  esteemed  by 
cats.  (8)  Hippuric  acid,  C6H5 .  CO . NH .  CH2 .  COOH  occurs 
in  the  urine  of  herbivorous  animals. 

The  so-called  carbohydrates  form  a  large  and  extremely 
important  group  of  compounds  of  carbon.  They  all  contain 
only  the  elements  carbon,  hydrogen,  and  oxygen,  and  more- 
over the  hydrogen  and  oxygen  are  always  present  in  the  same 
proportions  by  weight  as  in  water,  whence  the  name  carbo- 
hydrate. The  carbohydrates  consist  of  (1)  the  celluloses,  (2)  the 
starches,  (3)  the  gums  and  dextrines,  (4)  the  sugars. 

Wood,  cotton,  straw,  hemp,  linen,  etc.,  when  burnt  leave 
behind  a  certain  amount  of  ash,  but  aside  from  this,  which 
represents  their  mineral  content,  they  consist  of  almost  pure 
cellulose.  Cellulose,  then,  is  one  of  the  most  widely  distributed 
compounds  in  nature,  being  the  material  out  of  which  the 
cell  walls  of  all  plants  are  made.  The  composition  of  cel- 
lulose is  expressed  by  the  formula  (CeHioOs)^  Cellulose 
is  insoluble  in  water,  and  when  completely  burned  forms 
carbon  dioxide  and  water.  In  the  form  of  hay,  cornstalks, 
straw,  etc.,  cellulose  serves  as  a  food  for  cattle,  horses,  and  other 
herbivores,  but  human  beings  and  carnivorous  animals  can  not 
use  this  material  for  food.  It  is  evident,  however,  that  for 
fuel,  clothing,  and  shelter,  cellulose  in  various  forms  is  invaluable 
to  mankind.  Paper  is  made  from  rags,  straw,  wood  pulp, 
etc. ;  it  therefore  consists  of  fibers  of  cellulose  that  are  matted 
together.  Filter  paper  and  blotting  paper  are  unsized  papers ; 
whereas  writing  paper  and  many  other  papers  that  have  a 
hard,  smooth,  finished  surface  contain  rosin  which  has  been 


106  CHEMISTRY  AND   DAILY  LIFE 

melted  and  rolled  into  the  sheets  by  means  of  hot  rollers. 
The  surface  thus  finished  does  not  absorb  ink  so  readily,  and 
hence  serves  well  for  writing  purposes. 

Nitrates  of  cellulose  may  be  formed  by  treating  cellulose 
with  a  mixture  of  nitric  and  sulphuric  acids.  These  nitro- 
celluloses  are  true  esters  of  cellulose,  for  on  saponifying  them 
with  caustic  soda,  sodium  nitrate  and  cellulose  are  formed. 
Guncotton  is  cellulose  hexanitrate,  C^Hi^NOs^O^  It 
looks  much  like  ordinary  cotton,  but  it  is  harsher  to  the  touch 
and  on  ignition  it  burns  very  rapidly  and  quietly,  forming  no 
smoke.  Guncotton  can  be  made  to  explode  violently  by  means 
of  a  cap  of  fulminating  mercury.  The  latter  is  a  dangerous 
white  powder  that  results  when  mercury  is  acted  upon  by 
nitric  acid  in  presence  of  alcohol.  Guncotton,  then,  serves  as 
an  explosive.  It  may  be  used  alone  or  together  with  nitro- 
glycerine. The  latter  is  a  viscous  yellowish  liquid.  It  is 
the  nitrate  of  glycerine  and  is  produced  when  glycerine  is 
acted  upon  by  a  mixture  of  concentrated  nitric  and  sulphuric 
acids.  When  absorbed  in  diatomic  earth  and  molded  into 
sticks,  it  forms  dynamite.  Nitroglycerine,  like  guncotton, 
may  be  exploded  by  means  of  fulminating  mercury,  but  it 
may  also  explode  from  other  shocks  and  it  is  consequently  a 
very  dangerous  compound.  With  the  aid  of  vaseline  and  a 
solvent  like  acetone,  (CH3)2 .  CO,  guncotton  and  nitro- 
glycerine are  worked  into  threads  which  are  used  as  smokeless 
gunpowder.  Guncotton,  nitroglycerine,  and  dynamite  are 
used  in  the  arts  for  blasting  purposes.  They  have  also  sup- 
planted black  gunpowder  in  military  operations.  While 
gun  cotton  is  not  soluble  in  a  mixture  of  alcohol  and  ether, 
cellulose  tetranitrate  and  pentanitrate  are  soluble  in  this 
solvent  and  form  a  viscous  solution  that  is  known  as  collodion. 
It  is  used  for  making  films  in  photography,  and  in  medicine 
it  is  employed  in  dressing  wounds.  On  evaporation  of  the 


CARBON   AND   ITS   COMPOUNDS  107 

alcohol  and  ether  the  nitrocellulose  remains  as  a  tough 
transparent  film.  Celluloid  is  made  of  guncotton  and  camphor. 
It  is  therefore  a  highly  combustible  material,  and  this  fact 
should  always  be  borne  in  mind  in  using  it,  so  that  serious 
accidents  may  not  result  on  subjecting  it  to  heat  and  espe- 
cially to  flames. 

Starch,  too,  consists  of  carbon,  hydrogen,  and  oxygen,  and 
these  are  present  in  the  same  proportion  by  weight  as  in 
cellulose ;  but  they  are  combined  in  a  different  way  than  in 
the  latter.  Starch,  then,  has  the  formula  (CsH.i0Ob)x.  It 
will  not  dissolve  in  water,  but  when  a  little  of  it  is  rubbed 
fine  in  about  twice  its  volume  of  cold  water  and  then  ten  to 
twenty  times  that  volume  of  boiling  water  is  added  to  the  mix- 
ture with  constant  stirring,  starch  paste  results  which  is  used 
for  starching  clothes  ;  it  also  frequently  serves  as  an  adhesive. 
When  starched  clothes  are  afterwards  ironed,  a  gloss  is  pro- 
duced because  under  the  hot  iron  the  starch  is  converted  into 
dextrine  which  gives  the  luster  to  the  linen  fibers.  Starch 
occurs  in  all  plants,  especially  in  potatoes  and  other  tubers  and 
fleshy  roots,  but  also  in  grains  like  rice,  wheat,  rye,  oats,  barley, 
corn,  etc.  The  supply  of  starch  which  all  seeds  contain 
serves  to  nourish  the  young  plant  till  its  roots  and  tops  have 
developed  sufficiently  to  draw  sustenance  from  the  soil  and 
the  air.  In  this  process  starch  is  gradually  changed  to  sugar, 
and  the  latter,  being  soluble  in  water,  is  utilized  by  the  grow- 
ing embryonic  plant.  Starch  is  a  most  important  article  of 
food  for  man  and  animals  as  well.  Flour  consists  of  about 
70  per  cent  starch,  together  with  10  per  cent  gluten  (which 
is  a  nitrogen-bearing  substance  that  is  akin  to  the  albumins 
found  in  the  white  of  egg  and  hence  is  also  valuable  as  food) 
and  small  quantities  of  mineral  matter  (i.e.  ash),  water,  and 
sugar.  When  heated  to  210°  C.  starch  is  converted  to  dex- 
trine, C6HioO5,  which  is  a  colorless  amorphous  substance.  On 


108  CHEMISTRY  AND   DAILY  LIFE 

treatment  with  water  it  yields  a  sticky  mass,  and  hence  is 
very  commonly  used  as  a  cheap  adhesive  gum.  On  heating 
starch  with  dilute  sulphuric  acid,  it  is  converted  into  glucose. 
The  sulphuric  acid  may  afterwards  be  removed  by  treatment 
with  lime,  for  thus  insoluble  calcium  sulphate  is  produced. 

Sugars  may  be  divided  into  two  classes,  the  monoses  and  biases. 
The  monoses  have  a  composition  corresponding  to  the 
formula  C6Hi2O6,  and  the  common  representatives  of  this 
group  are  (1)  glucose  or  dextrose,  also  known  as  grape  sugar, 
(2)  levulose,  or  fruit  sugar,  also  called  fructose.  The  com- 
position of  the  bioses  corresponds  to  the  formula  Ci2H22On, 
and  the  chief  common  representatives  of  this  class  are  (1)  cane 
sugar,  also  called  saccharose  or  sucrose,  (2)  maltose,  or  malt 
sugar,  and  (3)  lactose,  or  milk  sugar. 

Glucose  is  found  in  the  juice  of  many  fruits,  especially  of 
grapes,  whence  the  name  grape  sugar.  Its  solutions  turn  the 
plane  of  polarized  light  to  the  right,  hence  this  sugar  is  also 
called  dextrose.  When  yeast  is  added  to  dilute  solutions  of 
dextrose,  fermentation  takes  place  and  alcohol  and  carbon 
dioxide  are  formed,  thus  : 

C6H12O6    (+    yeast)  =  2  C2H5OH     +     2  CO2 

glucose  alcohol  carbon  dioxide 

Solutions  of  glucose  precipitate  red  cuprous  oxide,  Cu2O,  from 
hot  Fehling's  solution.  The  latter  is  a  strongly  alkaline 
solution  of  copper  sulphate  and  Rochelle  salt,  sodium  potas- 
sium tartrate.  This  solution  is  much  used  in  testing  for  re- 
ducing sugars.  For  example,  by  this  means  in  the  case  of 
diabetic  patients  sugar  may  be  detected  in  the  urine.  By 
heating  starch  with  dilute  sulphuric  acid,  glucose  is  prepared 
on  a  large  scale,  as  already  mentioned  in  connection  with 
the  consideration  of  starch.  Thousands  of  tons  of  glucose  are 
thus  manufactured  from  corn  starch  annually  in  the  United 


CARBON  AND   ITS  COMPOUNDS  109 

States.  Glucose  is  a  good,  wholesome  food.  It  is  mainly  used 
in  candies,  table  sirups,  etc.  It  is  about  three-fifths  as  sweet 
as  cane  sugar. 

Levulose  or  fructose  is  also  found  in  the  juice  of  fruits. 
It  also  occurs  in  honey.  Its  solutions  turn  the  plane  of 
polarized  light  to  the  left,  whence  the  name  levulose;  they 
also  reduce  Fehling's  solution  yielding  a  precipitate  of  cu- 
prous oxide.  Furthermore  this  sugar,  too,  may  be  fermented 
with  yeast,  yielding  alcohol  and  carbon  dioxide. 

By  treating  cane  sugar  solutions  with  dilute  acids  both  dex- 
trose and  levulose  are  produced,  thus  : 


n  -f-  H^O  =  CeH^Oe  +  CeH^Oe 
cane  sugar          water          dextrose  levulose 

This  process  proceeds  quite  rapidly  on  heating  the  solution 
gently  to  boiling.  Since  the  resulting  liquid  turns  the  plane 
of  polarized  light  slightly  to  the  left,  whereas  the  original 
cane  sugar  solution  turned  the  plane  of  polarized  light  to  the 
right,  the  process  of  thus  changing  cane  sugar  to  dextrose  and 
levulose  is  commonly  termed  the  inversion  of  cane  sugar. 
The  latter  compound  does  not  alter  Fehling's  solution, 
whereas  it  will  be  recalled  that  both  dextrose  and  levulose 
effect  its  reduction. 

Cane  sugar  is  also  known  by  the  names  sucrose  and  saccharose. 
Sugar  cane  contains  from  15  to  20  per  cent  of  it,  whereas 
sugar  beets  commonly  yield  from  10  to  20  per  cent.  In 
sorghum,  in  maple  sap,  in  nuts,  and  in  the  blossoms  of  many 
plants  saccharose  abounds.  Indeed,  it  is  very  widely  dis- 
tributed in  the  vegetable  kingdom.  Rock  candy  is  almost 
pure  saccharose  and  exhibits  the  beautiful  monoclinic  prisms 
in  which  this  substance  crystallizes.  In  water  it  is  very 
soluble.  One  part  of  water  will  dissolve  three  times  its  weight 
of  sugar  at  room  temperature.  On  carefully  heating  cane 


110 


CHEMISTRY  AND   DAILY  LIFE 


sugar  it  may  be  melted  to  a  colorless  liquid  at  160°  C. ;  on 
cooling  this  yields  so-called  barley  sugar,  an  amorphous  glassy 
substance,  which  after  a  time  becomes  crystalline.  Caramel 
is  a  brown  substance  which  is  obtained  by  heating  sucrose 


FIG.  32.  —A  field  of  sugar  beets. 

to  about  200°  C.  Water  is  given  off  as  the  caramel  forms. 
The  latter  is  much  esteemed  in  candies.  Yeast  does  not  cause 
fermentation  of  cane  sugar  solutions  at  all  readily.  After  a  time, 
however,  fermentation  with  production  of  alcohol  and  carbon 
dioxide  does  occur,  for  yeast  contains  a  so-called  enzyme, 
invertase,  which  slowly  inverts  sucrose  to  glucose  and  levu- 
lose,  and  these  then  ferment.  In  manufacturing  sugar,  the 
juice  obtained  from  sugar  cane  or  sugar  beets  is  treated 
with  about  a  1  per  cent  solution  of  slaked  lime.  This  con- 
verts all  acids  present  to  calcium  salts,  serves  to  coagulate 


CARBON  AND   ITS   COMPOUNDS 


111 


proteins  present,  and  at  the  same  time,  being  an  antiseptic, 
it  guards  against  fermentation.  The  excess  of  lime  is  then 
removed  by  means  of  carbon  dioxide,  and  the  solution  is 
decolorized  by  filtering  through  bone  black,  after  which  it  is 


FIG.  33. — A  field  of  sugar  cane. 

evaporated  in  so-called  vacuum  pans  that  are  heated  by  means 
of  steam.  On  cooling,  crystals  of  sugar  separate  out.  These 
are  whirled  in  a  centrifuge  to  remove  the  adhering  brown 
liquid  in  which  they  grew.  The  latter  is  sold  as  molasses. 
Bagasse  is  the  name  given  to  the  residue  of  the  beets  or  cane 
after  the  removal  of  their  juice.  The  bagasse  is  used  as  fuel, 
made  into  paper,  or  fed  to  cows.  The  annual  production  of 


112  CHEMISTRY  AND   DAILY  LIFE 

sugar  from  beets  and  cane  is  about  ten  millions  of  tons,  which 
shows  that  it  is  used  very  extensively  as  a  food. 

Maltose  or  malt  sugar  occurs  in  malt.     Its  solutions  turn 
the  plane  of  polarized  light  to  the  right,  reduce  Fehling's 


FIG.  34.  —  Vacuum  pans  used  in  a  sugar  factory. 

solution,  and  readily  ferment  with  yeast  yielding  alcohol  and 
carbon  dioxide.  Maltose  is  an  intermediate  product  in  the 
formation  of  alcohol  from  starch,  for  when  diastase,  an  enzyme 
contained  in  malt,  acts  upon  starch,  maltose  is  produced. 
This  then  may  be  fermented  to  alcohol  and  carbon  dioxide. 
Upon  these  facts  the  commercial  production  of  fermented  liquors 
like  beer  depends.  The  dilute  alcoholic  solutions  obtained 
by  fermentation  may  be  concentrated  by  fractional  distilla- 
tion, thus  yielding  whisky,  gin,  rum,  and  even  alcoholic 
solutions  of  80  per  cent  and  still  higher.  Alcohol  that  is 
entirely  free  from  water  cannot  be  obtained  by  fractional 
distillation.  When  such  so-called  absolute  alcohol  is  re- 


CARBON  AND   ITS   COMPOUNDS 


113 


quired,  quicklime  is  added  to  alcohol  that  has  been  con- 
centrated by  distillation  as  far  as  it  is  profitable  to  do  so  by 
this  means.  The  lime  unites  with  the  water  present,  but 
not  with  the  alcohol,  and  the  latter  can  then  be  distilled  off. 


FIG.  35. — A  battery  of  centrifuges  used  in  drying  sugar  in  a  sugar  mill. 

When  maltose  is  treated  with  dilute  acids,  dextrose  only  is 
formed. 

Lactose  or  milk  sugar  occurs  in  the  milk  of  mammals.  Cow's 
milk  contains  about  5  per  cent  of  lactose.  It  is  not  as  sweet 
as  cane  sugar  and  far  less  soluble  in  water  than  the  latter. 
Six  parts  of  water  dissolve  about  1  part  of  lactose  at  room 
temperature.  Lactose  turns  the  plane  of  polarized  light  to 
the  right  and  reduces  Fehling's  solution,  but  not  as  readily  as 
maltose.  Toward  yeast  it  acts  much  like  cane  sugar,  that  is 
to  say,  fermentation  proceeds  but  very  slowly  indeed.  In  this 
case  the  products  formed,  however,  are  alcohol  and  lactic  acid. 
Yeast  that  is  quite  pure  does  not  ferment  lactose  at  all. 


114  CHEMISTRY  AND  DAILY  LIFE 

The  proteins,  formerly  called  proteids,  consist  of  carbon,  hy- 
drogen, oxygen,  nitrogen,  and  sulphur.  They  are  an  exceedingly 
important  class  of  substances,  for  ivhen  the  fats,  mineral  matter, 
and  water  are  taken  from  the  body  of  an  animal  what  is  left  con- 
sists entirely  of  proteins.  No  animal  can  live  without  proteins 
as  food.  The  composition  of  the  proteins  is  about  as  follows 
on  the  average :  carbon,  50.5  to  54.5  per  cent ;  oxygen,  21 
to  24  per  cent ;  nitrogen,  15  to  17.7  per  cent ;  hydrogen, 
6.5  to  7.3  per  cent ;  sulphur,  0.3  to  2.3  per  cent ;  phosphorus, 
0.4  to  0.8  per  cent.  The  nucleoproteins  so  called  often  con- 
tain 5  to  6  per  cent  of  phosphorus.  The  chemistry  of  the 
protein  bodies  is  quite  complicated,  and  only  of  recent  years 
has  notable  progress  toward  a  better  comprehension  of  the 
nature  of  these  substances  been  made.  Albumins  are  pro- 
teins, they  occur,  for  instance,  in  eggs,  in  muscles,  in  milk,  in 
blood  serum,  in  the  seeds  of  plants,  especially  in  beans,  peas, 
and  other  legumes.  The  albumins  may  be  coagulated  by 
means  of  heat,  also  by  means  of  acids.  The  name  albumi- 
noids is  given  to  a  class  of  protein  bodies  that  are  closely  re- 
lated to  the  albumins.  So,  for  example,  gelatin,  keratin,  and 
elastin  are  albuminoids.  Keratin  is  the  main  constituent 
of  hair,  hoofs,  horns,  feathers,  nails,  cuticle,  etc.,  while  elastin 
is  found  in  the  connective  tissues.  Peptones  are  formed 
when  albumins  are  acted  upon  by  pepsin,  an  enzyme,  or  so- 
called  unorganized  ferment.  In  the  change  from  albumin  to 
peptone,  water  is  added  to  the  compounds  by  the  action  of  pepsin. 
This  process  takes  place  in  the  stomach  and  is  important  in 
the  digestion  of  nitrogenous  foods. 

When  proteins  are  left  to  putrefy,  poisonous  substances 
called  ptomaines  are  produced,  among  which  putrescine 
C4H8(NH2)2  and  cadaverine  C5Hi0(NH2)2  may  be  mentioned. 
Poisoning  caused  by  eating  partially  decayed  meat,  fish,  or 
other  animal  food  is  generally  due  to  ptomaines. 


CARBON  AND   ITS   COMPOUNDS 


115 


In  plants  certain  non-nutritive  nitrogenous  constituents 
occur,  which  are  of  importance  in  common  life  and  ought 
consequently  to  be  mentioned  here.  These  substances 
consist  of  carbon,  hydrogen,  oxygen,  and  nitrogen.  They 
have  the  common  property  that  they  are  basic  in  character, 
that  is  to  say,  with  acids  they  form  salts.  Hence  these 
substances  are  called  alkaloids.  Only  a  few  of  the  most  im- 
portant will  be  mentioned.  Unless  otherwise  stated  they 
form  crystalline  solids. 

Quinine  C2oH24O2N2  and  cinchonine  Ci9H22ON2  occur 
in  Peruvian  bark.  The  sulphate  of  quinine  is  commonly 
used  in  treatment  of  malaria.  Morphine  CnHigOaN,  codeine 
Ci8H2iXO3,  and  narco- 
tine  C22H23O7N  occur  in 
opium,  the  dried  sap  of 
the  partially  ripe  pods  of 
the  opium  poppy.  Mor- 
phine is  used  to  produce 
sleep  and  is  commonly 
prescribed  as  the  hy- 
drochloride.  Strychnine 
C2iH22O2N2  and  brucine 
C23H26N2O4  are  found  in 
mix  vomica.  These  are 
extremely  bitter  and  wry  poisonous,  producing  death  with 
concomitant  convulsions  and  final  muscular  rigor.  Nicotine 
CioHi4N2  is  found  in  tobacco.  It  is  a  poisonous  liquid 
which  boils  at  247°  C.  Cocaine  CnHiC^N  occurs  in  coca 
leaves  and  is  used  as  a  local  anaesthetic.  Atropine  Ci7H23O3N 
is  found  in  nightshade,  the  deadly  Atropa  belladonna. 
Oculists  use  this  alkaloid  to  produce  expansion  of  the  pupil 
of  the  eye. 


FIG.  36. — An  oriental  poppy.     From  this 
plant  opium  is  obtained. 


116  CHEMISTRY  AND   DAILY  LIFE 

QUESTIONS 

1.  Make  a  list  of  the  various  forms  in  which  carbon  occurs. 
How  do  we  know  that  all  of  these  are  the  same  element  carbon? 

2.  Mention  the  uses  of  charcoal,  also  of  bone  black. 

3.  What  are  the  different  varieties  of  coal?    What  is  the 
essential  difference  between  them  ? 

4.  How  is  coal  gas  made  ?    What  does  it  contain  ? 

6.  Explain  how  it  is  that  ammonia  is  a  product  of  the  gas  works. 

6.  How  is  a  flame  produced  ?    Give  an  example. 

7.  What  causes  some  flames  to  be  luminous  and  others  to  be  non- 
luminous  ?     Give  examples  of  luminous  and  non-luminous  flames. 

8.  Draw  a  diagram  of  a  Bunsen  burner  and  explain  it. 

9.  What  are  the  properties  of  carbon  dioxide?     How  is  it 
formed  ?     How  does  it  occur  in  nature  ?     What  is  it  used  for  ? 

10.  How  is  carbon  monoxide  formed  ?    What  are  its  chief  char- 
acteristics ? 

11.  What  is  water  gas  ?    How  is  it  made  ? 

12.  How  is  starch  formed  ?     How  many  pounds  of  carbon  dioxide 
would  have  to  be  decomposed  to  form  5  pounds  of  starch  ? 

13.  What  is  the  so-called  carbon  cycle  ? 

14.  What  is  soda  water  ? 

15.  What  is  lime,  and  how  is  it  produced  ? 

16.  Explain  the  process  of  slaking  lime. 

17.  What  happens  when  lime  mortar  sets  ? 

18.  What  is  petroleum  ?    Mention  the  various  important  petro- 
leum products  that  are  on  the  market. 

19.  How  can  a  mineral  oil  be  distinguished  from  one  that  is  of 
plant  or  animal  origin  ? 

20.  What  is  acetylene  ?    How  many  grams  of  calcium  carbide  are 
necessary  to  make  100  liters  of  acetylene  at  0°  and  760  mm.  pressure  ? 

21.  What  is  the  difference  between  a  hydrocarbon  and  a  carbo- 
hydrate ?    Name  five  examples  of  each. 

22.  What  is  chloroform  ?     For  what  purpose  is  it  used  ? 

23.  What  is  carbon  tetrachloride  ?     What  are  its  uses  ? 

24.  How  may  fires  be  extinguished  ? 

25.  Why  should  water  not  be  used  to  extinguish  burning  oils  ? 


CARBON  AND  ITS  COMPOUNDS  117 

26.  What  is  wood  alcohol  ?    What  are  its  uses  ? 

27.  How  much  wood  alcohol  would  be  required  to  produce  two 
pounds  of  pure  formaldehyde  ? 

28.  What  is  formaline,  and  what  is  it  used  for  ? 

29.  How  is  ordinary  alcohol  produced  ?  *  What  are  its  uses  ? 

30.  How  much  grape  sugar  would  be  required  to  produce  100 
pounds  of  pure  alcohol  ? 

31.  What  is  vinegar  ?    How  is  it  produced  ? 

32.  What  is  denatured  alcohol  ?    Why  is  it  made  ? 

33.  What  is  glycerine  ?    How  is  it  produced  ? 

34.  How  are  alcohol  and  ether  related  chemically  ? 

36.  To  what  class  of  substances  do  the  plant  and  animal  fats  and 
oils  belong  ? 

36.  What  is  hard  soap  ?     Soft  soap  ? 

37.  What  is  meant  by  the  term  "hard  water"?     How  is  water 
softened  ? 

38.  What  is  carbolic  acid  ?     What  is  it  used  for  ? 

39.  Why  does  it  preserve  hams  and  fish  to  smoke  them  ? 

40.  What  is  benzene  ?    Benzoic  acid  ?     Aniline  ? 

41.  Mention  six  organic  acids  .and  tell  where  they  occur. 

42.  What  substances  are  called  carbohydrates  and  why  ?    Where 
do  these  occur  in  nature  ? 

43.  Which  of  the  carbohydrates  serve  as  human  food  ?  Classify 
the  carbohydrates. 

44.  To  what  animals  may  cellulose  serve  as  food  ?    Will  cellulose 
in  any  form  do  for  this  purpose  ?    Explain  by  a  few  examples. 

45.  What    is    guncotton?     Dynamite?    Smokeless    powder? 
Celluloid? 

46.  What  are  the  properties  of  starch  ?    How  test  for  the  pres- 
ence of  starch  ? 

47.  What  is  flour? 

48.  Classify  the  sugars,  and  give  the  chief  characteristics  of  each 
of  the  principal  sugars. 

49.  What  is  a  protein  ?    Give  several  examples. 

60.  To  what  class  of  bodies  do  morphine,  quinine,  and  strychnine 
belong  ? 


CHAPTER  X 


THE    METALS    OF   THE    ALKALIES   AND    THE 
ALKALINE    EARTHS. 

THE  metals  of  the  alkalies  are  potassium,  sodium,  lithium, 
ccesium,  and  rubidium.  The  last  two  are  of  such  rare  occur- 
i rence  that  they  will  not  be  con- 
sidered here.  Even  lithium  is 
found  only  in  small  amounts.  It 
occurs  in  certain  micas  and  some- 
times in  a  few  plants  like  tobacco 
and  beets.  In  general  its  proper- 
ties, and  also  those  of  caesium  and 
rubidium,  are  similar  to  the  prop- 
erties of  potassium  and  sodium. 
The  metals  of  the  alkalies  never 
occur  in  nature  in  the  free  or  un- 
combined  state.  They  are  only 
found  with  other  elements  in  the 
form  of  salts. 

Plant  ashes  always  contain  po- 
tassium carbonate,  K^COa,  also 
called  potash.  It  has  long  been 
the  practice  to  leach  out  wood 
ashes  with  water,  and  use  the 
potash  solution  thus  obtained  for 
the  purpose  of  making  soap. 

Potassium  is  an  element  that  is  essential  to  plant  and  animal 
life.     Without  potassium  salts  plants  cannot  grow.     All  soils 

118 


FIG.  37. — Buckwheat.  On  the 
right  all  the  elements  are  pres- 
ent ;  on  the  left  all  except  po- 
tassium. 


THE  METALS  OF  THE  ALKALIES 


119 


contain  potassium  in  the  form  of  soluble  salts,  although  in 
most  cases  in  insufficient  quantity.  For  this  reason,  it  has 
long  been  the  practice  to  return  potassium  salts  to  the  land. 
Certain  quantities  get  back  through  the  application  of  stable 
manure.  Wood  ashes  are  commonly  applied  to  fields  when  pot- 
ash is  lacking.  Feldspar,  which  is  a  silicate  of  potassium  and 


FIG.  38.  —  Geological  formation  of  the  Stassfurt  salt  beds. 

aluminium,  occurs  in  all  granitic  rocks  and  in  many  clay  soils, 
and  plants  secure  notable  amounts  of  potash  from  this  source, 
for  the  soil  waters  gradually  extract  potash  from  the  feldspar, 
though  this  process  is  quite  slow.  The  largest  bed  of  potassium 
salts  found  in  nature  is  that  at  Stassfurt  in  Germany.  Here 
potassium  occurs  chiefly  as  carnallite  KC1 .  MgCl2 . 6  H2O  and 
as  kainite  KC1 .  MgSO4 .  3  H2O.  It  is  also  found  there  as 
sylvite,  muriate  of  potassium,  KC1,  to  some  extent.  The 
potassium  salt  deposits  at  Stassfurt  form  layers  varying  in 
thickness  from  sixty  to  one  hundred  feet.  They  rest  upon 
thick  beds  of  common  salt.  Practically  the  entire  supply 
of  potassium  salts  of  the  world  is  derived  from  this  enormous 


120  CHEMISTRY  AND   DAILY  LIFE 

deposit.  However,  in  small  amounts  potassium  salts  are 
found  very  widely  distributed.  So  potassium  occurs  not  only 
in  all  plants,  but  in  bones,  muscles,  blood,  milk,  albumin,  and 
the  various  secretions  of  animals.  The  earth's  crust  contains 
about  2.45  per  cent  potassium,  and  in  oceanic  water  there  is 
about  0.04  per  cent. 

Caustic  potash,  potassium  hydroxide,  KOH,  may  be 
obtained  by  treating  potassium  carbonate  with  slaked  lime, 
thus: 

K2CO3    +  Ca(OH)2    =    CaCO3       +     2  KOH 

potassium  calcium        calcium  carbonate     caustic  potash  or 

carbonate  hydroxide  (insoluble)          potassium  hydroxide 

Large  quantities  of  potassium  hydroxide  are  now  prepared  by 
electrolysis  of  potassium  chloride,  muriate  of  potash.  Thus 
this  salt  is  decomposed  into  chlorine  and  potassium,  and  when 
the  latter  acts  on  water,  hydrogen  and  potassium  hydroxide 
are  formed ;  the  reactions  involved  are  therefore  : 

2  KC1  by  electrolysis   =   2  K  +  C12 
and  2  K  +  2  H20          =2  KQH  +  H2 

By  boiling  down  caustic  potash  solutions  (which  must  be  done 
in  silver  or  iron  vessels,  for  glass  or  porcelain  would  be 
strongly  attacked  by  the  lye)  solid  potassium  hydroxide  may 
be  obtained.  It  is  a  white,  hard,  brittle  solid  which  dissolves 
very  readily  in  water  with  evolution  of  considerable  heat. 
Its  solutions  corrode  and  disintegrate  animal  and  vegetable 
tissues,  hence  the  name  caustic  potash.  It  is  used  in  making 
soft  soap,  being  placed  on  the  market  as  potash  lye.  On  neu- 
tralization with  acids,  it  forms  various  potassium  salts. 
A  few  of  the  most  important  ones  will  now  be  described. 

Potassium  carbonate  has  already  been  mentioned.  While 
it  was  formerly  derived  almost  entirely  from  wood  ashes,  it  is 
now  made  from  the  Stassfurt  salts  by  a  method  similar  to 


THE   METALS  OF  THE  ALKALIES  121 

that  of  preparing  sodium  carbonate  by  the  so-called  LeBlanc 
process  (which  see).  Potassium  carbonate  is  also  known 
commercially  as  pearlash.  It  is  employed  in  the  manufacture 
of  soft  soap,  hard  glass,  and  various  salts  of  potassium. 

Saltpeter,  potassium  nitrate,  KNO3,  is  present  in  small 
amounts  in  all  soils.  It  is  a  white  crystalline  salt.  At 
ordinary  temperatures  100  parts  of  water  dissolve  13  parts 
of  potassium  nitrate,  but  the  same  amount  of  boiling  water 
dissolves  247  parts  of  this  salt.  Saltpeter  is  prepared  com- 
mercially by  adding  potassium  chloride  (from  the  Stassfurt 
deposits)  to  hot  saturated  solutions  of  Chili  saltpeter,  NaNO3, 
thus: 

NaNO3     +    KC1      =     NaCl     +     KNO3 

sodium  nitrate       potassium      sodium  chloride      potassium 
chloride  nitrate 

The  common  salt,  NaCl,  is  not  nearly  as  soluble  as  the  potas- 
sium nitrate,  consequently  the  latter  remains  dissolved  while 
the  former  is  precipitated.  From  the  clear  solution,  crystals 
of  potassium  nitrate  are  then  obtained  on  cooling.  Salt- 
peter is  used  in  the  manufacture  of  black  gunpowder,  which 
consists  of  75  parts  saltpeter,  11  parts  sulphur,  and  17. 5  parts 
charcoal.  When  it  is  exploded  a  portion  of  the  latter  ingre- 
dient always  remains  unoxidized  and  so  forms  black  smoke. 
The  use  of  black  gunpowder  in  war  is  now  a  thing  of  the  past. 
Saltpeter  is  also  used  in  salting  meats;  so,  for  example,  60 
parts  of  common  salt,  1  part  of  saltpeter,  and  10  parts  of 
sugar,  all  dissolved  in  400  parts  of  water,  make  a  good  solu- 
tion for  salting  beef  or  pork. 

Potassium  chloride,  KC1,  is  a  white  crystalline  salt.  It  is 
readily  soluble  in  water  and  tastes  salty.  It  is  chiefly 
obtained  from  the  Stassfurt  deposits  and  is  the  commonest 
and  cheapest  of  the  potassium  salts.  In  crude  form  it  serves 
as  a  fertilizer.  From  it  caustic  potash,  saltpeter,  and  other 


122  CHEMISTRY  AND   DAILY  LIFE 

potassium  salts  are  prepared.  This  salt  is  also  found  in  sea 
water.  In  the  blood  and  urine  of  herbivorous  animals  it  is 
also  present  in  minute  amounts. 

Potassium  bromide,  KBr,  and  potassium  iodide,  KI, 
crystallize  in  cubes,  which  are  extremely  soluble  in  water. 
Both  of  these  salts  are  used  in  medicine  and  in  photography. 

Potassium  chlorate,  KC1O3,  is  produced  by  conducting 
chlorine  into  hot  solutions  of  caustic  potash,  thus  : 

6  KOH  +  3  C12     =     KC103     +     5  KC1  +  3  H2O 

caustic  potash      chlorine  potassium  potassium          water 

chlorate  chloride 

By  electrolyzing  hot  potassium  chloride  solutions  both  caustic 
potash  and  chlorine  are  simultaneously  formed,  and  so  most 
of  the  potassium  chlorate  in  the  market  is  prepared  by  this 
means.  Potassium  chlorate  is  used  in  making  oxygen,  matches, 
fireworks,  and  explosives.  It  is  also  used  in  medicine,  particu- 
larly as  a  gargle  for  sore  throat. 

Potassium  silicate,  K2SiO3,  is  made  by  fusing  sand  with 
potassium  carbonate,  thus : 

Si02  +  K2C03  =   K2Si08      +      C02 

silica          potassium         potassium          carbon  dioxide 
carbonate  silicate 

This  salt  is  soluble  in  water  and  its  sirupy  solutions  are 
popularly  called  potassium  water  glass. 

Potassium  sulphate,  K2SO4,  is  found  at  Stassfurt  in  kainite. 
It  is  also  a  constituent  of  potassium  alum.  In  crude  form 
it  serves  as  a  fertilizer.  It  is  employed  in  the  manufacture  of 
hard  glass,  alum,  and  potassium  carbonate. 

Potassium  phosphate,  K2HPO4,  is  present  in  minute 
amounts  in  the  blood  and  urine  of  all  carnivores.  It  is  a 
white  crystalline  salt  which  dissolves  readily  in  water. 

Potassium  cyanide,  KCN,  is  an  extremely  poisonous  salt.    It 


THE   METALS   OF  THE  ALKALIES  123 

is  used  in  photography,  in  extracting  gold  from  its  ores, 
in  gold  and  silver  plating,  and  also  in  preparing  hydro- 
cyanic acid  gas,  HCN,  for  fumigating  trees.  Potassium 
cyanide  and  hydrogen  cyanide  (also  known  as  Prussic  acid) 
are  terrible  poisons  and  must  be  used  with  extreme  care. 

To  the  Bunsen  flame  potassium  salts  impart  a  beautiful 
violet  color. 

Metallic  potassium  itself  was  prepared  in  1807  by  elec- 
trolysis of  molten  caustic  potash  by  Sir  Humphry  Davy. 
Its  specific  gravity  is  0.865  at  15°  C.  The  metal  is  rather 
soft,  melts  at  62°.5  C.,  and  boils  at  667°  C.  With  water 
it  reacts  violently,  forming  hydrogen  and  caustic  potash, 
hence  the  metal  must  be  kept  under  petroleum  oils  to  protect 
it  from  the  moisture  of  the  air. 

Metallic  sodium  and  metallic  lithium  have  properties  that 
are  in  general  similar  to  those  of  metallic  potassium.  They 
may  be  obtained  by  electrolysis  of  molten  caustic  soda, 
NaOH,  and  caustic  lithia,  LiOH,  respectively.  Sodium  and 
lithium  are  therefore  also  kept  under  petroleum  tb  protect 
them  from  the  moisture  of  the  air.  Sodium  is  silver-white, 
somewhat  harder  than  potassium,  melts  at  95°.5  C.  and  boils 
at  742°  C.  At  15°  C.  its  specific  gravity  is  0.974. 

All  sodium  salts  are  soluble  in  water.  To  the  Bunsen  flame 
they  all  impart  a  yellow  color,  whereas  lithium  salts  color 
the  flame  a  characteristic  red. 

In  general  the  sodium  salts  are  similar  to  those  of  potassium. 
The  chief  source  of  all  sodium  compounds  is  common  salt, 
sodium  chloride,  NaCl,  which  occurs  in  the  sea,  in  the  waters 
of  salt  lakes  and  wells,  and  also  in  layers  in  solid  form,  par- 
ticularly at  Stassfurt  and  Reichenhall  in  Germany,  in  Galicia, 
in  England,  in  the  states  of  New  York,  Michigan,  Texas, 
Utah,  and  California,  also  in  Africa  and  Asia.  Salt  is  very 
widely  distributed  on  the  globe.  It  is  necessary  to  animal  life, 


124  CHEMISTRY  AND  DAILY  LIFE 


SIR  HUMPHRY  DAVY,  1778-1829,  the  discoverer  of  the  alkali  metals. 


THE   METALS  OF  THE  ALKALIES  125 

and  occurs  in  the  blood,  the  tissues,  and  all  of  the  secretions. 
Just  as  land  plants  take  up  potassium  chloride,  so  sea  plants 
take  up  common  salt.  Common  salt  crystallizes  in  cubes 
and  melts  at  about  800°  C.  It  is  about  as  soluble  in  cold  as 
in  hot  water.  At  room  temperature  100  parts  of  water  dis- 
solve 36  parts  of  salt,  while  the  same  amount  of  boiling  water 
dissolves  but  39  parts.  The  United  States  alone  produces 
nearly  four  and  one-half  million  tons  of  salt  annually  and  this 
is  only  about  one-fourth  of  the  world's  yearly  production. 
Salt  is  used  for  making  chlorine,  hydrochloric  acid,  caustic 
soda,  sodium  carbonate,  and  other  sodium  compounds. 

Caustic  soda,  sodium  hydroxide,  NaOH,  is  quite  similar 
to  potasium  hydroxide  in  its  properties  and  is  prepared  in  an 
analogous  manner.  It  is  used  in  making  hard  soap,  also 
in  "  softening  "  water.  It  is  further  employed  in  the  manu- 
facture of  carbolic  acid  and  oxalic  acid,  also  in  making  paper 
and  other  articles.  Being  cheaper  than  caustic  potash,  it  is 
used  in  place  of  the  latter  whenever  it  is  possible. 

Sodium  carbonate,  Na2CO3,  is  also  often  called  sal  soda,  or 
soda.  Just  as  potassium  carbonate  or  potash  occurs  in  the 
ashes  of  land  plants,  so  soda  is  found  in  the  ashes  of  marine 
plants.  Soda  is  used  to  make  common  glass,  hard  soap,  and 
many  other  sodium  compounds.  It  is  therefore  manufactured 
on  a  very  large  scale.  There  are  two  processes  of  manufactur- 
ing soda,  namely,  the  LeBlanc  process  and  the  Solvay  process. 
Both  utilize  common  salt  as  the  raw  material. 

In  the  LeBlanc  soda  process  salt  is  first  treated  with  sul- 
phuric acid,  thus : 

2  NaCl  +  H2SO4  =  NaCl  +  NaHSO4  +  HC1 

salt        sulphuric  acid  salt  cake  hydrochloric 

acid 

The  so-called  "  salt  cake  "  consists  of  salt  and  acid  so- 
dium sulphate.  This  is  then  heated  in  a  suitable  fur- 


126  CHEMISTRY  AND   DAILY  LIFE 

nace,    thus  forming   more   hydrochloric   acid,    and  sodium 
sulphate: 


4  =  NaaSO4  +  HC1 

salt  cake  sodium      hydrochloric 

sulphate  acid 

The  sodium  sulphate  is  then  mixed  with  charcoal  and  cal- 
cium carbonate  and  heated  in  a  rotary  furnace  ;  in  this  way 
carbon  monoxide  escapes  and  calcium  sulphide  and  soda  are 
formed,  thus  : 

Na2SO4      +       4C  Na*S       +        4  CO 

sodium  sulphate  carbon  sodium  sulphide        carbon  monoxide 

and    Na2S       +       CaCO3       =       Na2CO3       +       CaS 

sodium  calcium  soda  calcium 

sulphide  carbonate  sulphide 

The  entire  mass  is  then  treated  with  water.  The  sodium 
carbonate  dissolves  and  calcium  sulphide  remains  as  an  in- 
soluble residue.  From  the  clear  solution,  crystals  are  ob- 
tained which  have  the  composition  Na2CO3  .  10  H2O.  This 
is  so-called  washing  soda  or  crystallized  soda.  On  heating 
the  crystals  they  lose  water  and  form  calcined  soda  or  an- 
hydrous sodium  carbonate,  Na2CO3. 

By  the  Solvay  process,  sodium  bicarbonate,  NaIICO3,  is 
first  obtained.  This  salt  is  relatively  less  soluble  than  the 
corresponding  ammonium  salt,  ammonium  bicarbonate, 
NH4HCO3,  which  may  be  obtained  when  carbon  dioxide  is 
passed  into  strong  ammonia  water,  thus  : 

NH4OH  +  CO2  =  NH4HCO3 

ammonium        carbon        ammonium 
hydroxide         dioxide        bicarbonate 

On  treatment  of  a  saturated  solution  of  sodium  chloride 
with  ammonium  bicarbonate,  sodium  bicarbonate  is  precip- 
itated, thus  : 

NaCl  +  NH4HCO3   =   NaHCO3  +  NH4C1 

-    salt  ammonium  sodium  ammonium 

bicarbonate  bicarbonate  chloride 


THE   METALS   OF  THE  ALKALIES 


127 


The  ammonium  chloride  remains  in  solution.  In  actual 
practice,  then,  the  Solvay  process  consists  in  conducting  both 
ammonia  and  carbon  dioxide  into  a  saturated  solution  of  com- 
mon salt.  Thus  both  of  the  changes  expressed  by  the  last 
two  equations  take  place  together.  Sodium  bicarbonate  is 
also  called  saleratus  or  baking  soda.  It  has  a  mild  alkaline 


mz 


M?t 


^>P;^- 


Y  .v?« 

FIG.  39.  —  A  Chilian  saltpeter  bed. 

reaction,  and  is  used  in  medicine,  in  baking  powders,  etc. 
On  heating  sodium  bicarbonate  it  loses  water  and  carbon 
dioxide  and  forms  sodium  carbonate,  thus  : 

2  XaHCO3   =   Na2CO3  +  H2O  +  C02 

Even  when  solutions  of  sodium  bicarbonate  are  heated,  car- 
bon dioxide  is  evolved ;  upon  this  fact  the  use  of  saleratus  in 
baking  depends. 

Sodium  nitrate,  XuXO3,  is  found  in  large  beds  in  Chili  and 
is   consequently  known    as   Chili  saltpeter.     With  it  occur 


128  CHEMISTRY  AND  DAILY  LIFE 

smaller  amounts  of  sodium  chloride,  sodium  sulphate,  and 
sodium  iodate,  NaIO3.  The  latter  compound  is  the  chief 
commercial  source  of  iodine.  Sodium  nitrate  is  used  as  a 
fertilizer  on  account  of  its  nitrogen  content.  It  also  is  em- 
ployed in  large  quantities  in  making  nitric  acid,  thus : 

NaN03  +  H2SO4  =  NaHS04  +  HNO3 
Sodium  nitrate  should  be  added  to  the  soil  only  in  small  amounts 
at  a  time. 

Sodium  sulphate,  Na2SO4,  is  formed  as  one  of 'the  products 
of  the  Leblanc  soda  process.  It  dissolves  readily  in  water, 
and  when  it  crystallizes  from  the  latter  at  room  temperatures 
beautiful  crystals  of  the  composition  Na2SO4 . 10  H2O  are 
formed.  This  is  the  so-called  Glauber's  salt,  which  is  so 
much  used  as  a  laxative.  It  was  first  made  by  Johann  Rudolf 
Glauber  in  1658. 

Sodium  sulphite,  Na2SO3,  is  made  by  passing  sulphur 
dioxide  into  sodium  hydroxide  solution.  This  salt  is  used 
in  photography. 

Sodium  thiosulphate,  Na2S2O3 . 5  H2O,  is  *the  so-called 
" hyposulphite  of  soda"  or  "hypo,"  so  much  used  in  making 
the  "fixing  bath"  in  photography.  It  is  produced  by  boil- 
ing a  solution  of  sodium  sulphite  with  flowers  of  sulphur. 

Sodium  silicate,  Na2SiO3,  or  sodium  water  glass,  is  produced 
by  fusing  silica  with  sodium  carbonate  or  with  a  mixture  of 
carbon  and  Glauber's  salt.  In  laundry  soaps  it  serves  as  a 
"  filler."  It  is  also  employed  in  cementing  together  the  fibers 
of  mineral  wool  and  asbestos,  and  in  fireproofing  wood,  fab- 
rics, etc. 

Borax  has  the  composition  Na2B4O7 . 10  H2O.  Its  uses 
have  already  been  mentioned. 

The  metals  of  the  alkaline  earths  are  barium,  strontium, 
calcium,  and  magnesium.  They  are  so  called  because  their 
respective  oxides  BaO,  SrO,  CaO,  and  MgO  are  alkaline, 


THE  METALS  OF  THE  ALKALIES  129 

which  fact  is  apparent  when  they  are  treated  with  moist 
red  litmus  paper,  for  example.  These  metals  may  be  pre- 
pared by  the  electrolysis  of  their  molten  chlorides.  They  all 
are  silver-white  in  appearance,  and  when  treated  with  water 
they  yield  hydrogen  and  the  hydroxide  of  the  metal  em- 
ployed. The  hydroxides  are  soluble  in  water,  but  not  copi- 
ously. 

The  chief  source  of  barium  is  barium  sulphate,  BaSO4,  also 
called  heavy  spar  or  "  barytes."  It  occurs  in  nature  in 
fairly  pure  form  in  compact  masses.  Its  specific  gravity  is 
4.48.  Ground  to  powder,  it  serves  as  a  white  pigment  in 
paints,  being  called  "  permanent  white."  It  is  not  infre- 
quently used  as  a  cheap  adulterant  in  white  lead,  a  practice 
that  is  to  be  condemned.  Barium  sulphate  is  almost  com- 
pletely insoluble  in  water  and  also  in  dilute  acids.  It  pre- 
cipitates whenever  a  solution  of  a  sulphate  is  treated  with 
barium  chloride  solution  or  a  solution  of  any  other  barium 
salt,  so,  for  instance  : 

CuSO4       +        BaCl2  BaSO4       +       CuCl2 

copper  sulphate         barium  chloride         barium  sulphate         copper  chloride 

Barium  chloride  is  consequently  very  commonly  used  in  testing 
for  sulphates,  also  for  determining  the  amount  of  sulphur 
present  in  a  compound,  for  the  latter  process  commonly  con- 
sists of  converting  the  sulphur  into  a  soluble  sulphate  and 
then  precipitating  barium  sulphate  by  adding  an  excess  of 
barium  chloride  solution.  From  the  amount  of  barium 
sulphate  formed  the  amount  of  sulphur  may  be  computed, 
for  the  composition  of  barium  sulphate  is  well  known. 
Barium  nitrate,  Ba(NO3)2,  is  used  for  making  green  Bengal 
lights.  Barium  salts  are  all  poisonous.  Cattle  in  our 
Western  states  have  been  reported  as  seriously  poisoned  by 
eating  herbs  that  had  taken  up  barium  from  the  soil.  This 


130  CHEMISTRY  AND  DAILY  LIFE 

is,  of  course,  very  unusual,  for  barium  is  ordinarily  not 
found  in  soils. 

Strontium  compounds  are  entirely  similar  to  those  of 
barium,  only  they  are  of  rarer  occurrence.  Strontium  ni- 
trate, Sr(NO3)2,  is  used  in  fireworks  and  for  making  red  Bengal 
lights.  All  strontium  salts  color  the  Bunsen  flame  red, 
while  those  of  barium  color  it  green,  and  calcium  compounds 
produce  an  orange-yellow  color. 

Calcium  carbonate,  CaC03,  is  found  in  large  quantities  in 
nature  as  limestone,  marble,  and  chalk.  Iceland  spar  or  calcite 
is  a  very  pure  crystalline  form  of  calcium  carbonate.  When 
limestone  occurs  mixed  with  clay,  it  is  called  marl.  Calcium 
sulphate,  CaSO4,  occurs  as  anhydrite,  gypsum,  CaSO4 .  2  H2O, 
and  alabaster.  In  natural  waters  calcium  bicarbonate  and 
calcium  sulphate  are  quite  commonly  found.  They  produce 
the  hard  sediments  in  teakettles,  boilers,  etc.  These 
sediments  generally  also  contain  silica,  oxides  of  iron,  alu- 
minum, magnesium,  etc.  These  have  been  dissolved  from 
the  rocks  or  soils  with  which  the  waters  have  come  in  contact. 

Marble  and  limestone  serve  as  building  stones,  also  for 
making  lime,  glass,  and  cement,  and  reducing  iron  ores.  In 
the  form  of  chalk  calcium  carbonate  is  used  as  whiting,  which 
when  ground  up  with  linseed  oil  forms  putty. 

Lime,  CaO,  is  made  by  heating  limestone  or  marble  in 
kilns.  Thus,  carbon  dioxide  is  driven  off  and  the  oxide  of 
calcium  remains : 

CaCO3  on  heating  =  CaO       +      CO2 

limestone  lime  carbon  dioxide 

The  slaking  of  lime  and  its  use  in  making  mortar  have  already 
been  described. 

Calcium  chloride,  CaCl2,  is  formed  when  hydrochloric  acid 
acts  on  limestone,  thus  : 


THE   METALS   OF  THE   ALKALIES 


131 


CaC03 

limestone 


2HC1     = 

hydrochloric 
acid 


CaCl2 

calcium 
chloride 


H20 

water 


C02 

carbon  dioxide 


Calcium  chloride  is  very 
soluble  in  water,  and  its 
brines  are  commonly  used 
as  the  cold  liquid  that  cir- 
culates in  the  pipes  in  re- 
frigerators. This  brine 
is  kept  cold  by  means  of 
evaporation  of  ammonia 
which  has  been  liquefied 
under  pressure. 

On  carefully  heating 
gypsum,  CaSO4 .  2  H2O, 
to  about  110°  it  loses 
water  and  becomes 
CaSO4 .  |  H2O,  which  is 
known  as  plaster  of 
Paris.  When  it  is  af- 
terward mixed  with 
water,  the  whole  sets  or 
hardens  to  a  solid  mass, 
which  depends  upon  the 
fact  that  plaster  of  Paris 
and  water  unite  and  again  form  gypsum,  thus : 

CaSO4 .  J  H2O  +  1}  H2O  =  CaSO4 .  2  H2O 

plaster  of  Paris  water  gypsum 

Plaster  of  Paris  is  much  used  in  making  hard  wall  plaster, 
gypsum,  calsomine,  casts,  and  bandages  in  surgery. 

As  all  plants  and  animals  contain  sulphur  and  calcium 
salts,  calcium  sulphate  in  the  form  of  gypsum  is  commonly 
used  as  a  fertilizer  under  the  name  of  land  plaster. 


FIG.  40.  — A  modern  lime  kiln. 


132 


CHEMISTRY  AND  DAILY  LIFE 


Calcium       nitrate, 

Ca(NO3)2,  is  very  soluble 
in  water.  It  is  formed 
in  composted  manure, 
and  also  on  the  white- 
washed walls  of  stables. 
The  ammonia  present  in 
the  stable  air  is  gradually 
oxidized  to  nitric  acid, 
which  then  attacks  the 
calcium  carbonate  on  the 
walls,  forming  calcium 
nitrate  and  carbon  di- 
oxide. This,  of  course, 
destroys  the  wall  coat- 
ing. The  calcium  nitrate 
in  the  soil  is  a  good  plant 
food,  for  it  contains  both 
calcium  and  nitrogen  in 
available  form. 

Calcium  phosphate, 
Ca3(PO4)2,  is  insoluble  in 
water  but  soluble  in  di- 
lute acids.  It  occurs  in 
crystals  as  apatite,  is  the  chief  constituent  of  bones,  and  is 
found  in  phosphate  rock,  guano,  and  barnyard  manure.  The 
fact  that  by  treating  bones  or  phosphate  rock  with  sul- 
phuric acid,  superphosphate  fertilizer  is  formed  has  already 
been  mentioned.  Over  two  and  one-half  million  tons  of  phos- 
phate rock  are  used  annually  in  the  United  States  as  fertilizer. 
The  exportation  of  phosphate  rock  should  be  forbidden  by 
law,  for  the  supply  of  this  important  material,  without  which 
agriculture  cannot  thrive,  is  limited.  The  beds  of  phosphate 


FIG.  41.  — A  broken  leg  in  a  plaster  of 
Paris  cast. 


THE   METALS   OF  THE  ALKALIES  133 

rock  occur  mainly  in  Florida  and  South  Carolina,  but  re- 
cently deposits  have  also  been  found  in  some  of  the  Rocky 
Mountain  states. 

As  calcium  silicate,  calcium  occurs  in  many  rocks,  espe- 
cially in  complex  silicates  like  feldspars,  garnet,  mica,  horn- 
blende, etc. 

Portland  cement  is  made  by  heating  limestone  together 
with  aluminum  silicates  in  a  kiln,  and  then  grinding  up  the 
clinker  to  a  fine  powder.  This  is  usually  grayish  or  grayish 


FIG.  42.  —  Concrete  fence  posts. 

brown  in  color.  When  mixed  with  water  it  will  unite  with  the 
latter,  forming  a  hard  stonelike  mass  which  in  appearance 
resembles  the  native  stone  found  at  Portland,  England, 
whence  the  name  Portland  cement.  No  chemical  formula  can 
be  given  for  Portland  cement,  but  a  good  Portland  cement 
must  contain  silica,  SiO2,  from  20  to  25  per  cent ;  lime,  CaO, 
from  58  to  65  per  cent;  alumina,  from  5  to  10  per  cent. 
Magnesia,  MgO,  must  not  exceed  5  per  cent,  and  the  less 


134  CHEMISTRY  AND   DAILY  LIFE 

there  is  of  it,  the  better.  Iron  oxide,  Fe2O3,  may  be  present 
in  notable  quantities  without  doing  harm ;  it  is  commonly 
found  in  cements  to  the  extent  of  from  2  to  5  per  cent.  Other 
impurities,  like  small  amounts  of  soda,  potash,  and  sul- 
phates, are  generally  also  found,  commonly  less  than  1 
per  cent. 

At  Milwaukee,  Louisville,  and  Rosendale,  N.Y.,  occur 
natural  deposits  of  limestone  that  contain  almost  the  right 
amounts  of  aluminum  silicates  to  make  Portland  cement. 
This  material  is  heated  in  kilns,  and  the  resulting  clinker  is 
then  ground  up  and  sold  as  "  natural  cement."  While 
quite  serviceable  for  many  purposes  and  cheaper  than  Port- 
land cement,  it  nevertheless  is  not  equal  to  the  latter  in 
wearing  qualities.  Portland  cement  sets,  even  under  water, 
and  hence  can  be  used  in  damp  places  where  ordinary  lime 
mortar  will  not  harden  at  all.  Mixed  with  sand  and  crushed 
stone  or  gravel  and  then  saturated  with  water,  Portland 
cement  forms  so-called  concrete.  In  modern  structures, 
iron  or  steel  rods  or  networks  of  wires  are  often  embedded  in 
concrete  to  strengthen  it.  This  is  then  known  as  reenforced 
concrete.  It  is  much  used  in  erecting  bridges,  fireproof 
buildings,  etc.  Nearly  fifteen  thousand  tons  of  Portland 
cement  are  produced  annually  in  the  United  States  alone. 
The  slags  from  blast  furnaces,  which  contain  silica,  alumina, 
and  lime,  are  now  also  used  in  the  manufacture  of  Portland 
cement,  the  lacking  ingredients  being  added,  of  course,  before 
firing  the  material  in  the  kiln.  The  cements  from  blast  fur- 
nace slag  are  generally  richer  in  iron  and  browner  in  color  than 
other  cements.  They  are  of  very  good  quality,  nevertheless. 

Glass  commonly  consists  of  a  mixture  of  the  silicates  of 
calcium  and  sodium.  It  is  made  by  melting  together  silica, 
SiO2,  limestone,  CaCOs,  and  soda,  Na2CO3.  The  final  product 
corresponds  approximately  to 'the  composition 


THE   METALS   OF  THE  ALKALIES 
CaO .  3  SiO2  -f  Na20  .  3  SiO2 


135 


and  is  known  as  soft  glass  or  soda  lime  glass.  It  is 
used  in  making  windows,  bottles,  and  ordinary  glass  dishes. 
The  mixture  is  melted  in  pots  of  fire  clay  about  four 
feet  high  and  four  feet  in  diameter.  Potash  lime  glass 


(A)  (B) 

FIG.  43.  —  (A)   Blowing  a  glass  bottle.     (B)    Making  window  glass. 

is  hard  glass.  It  is  also  called  Bohemian  glass.  It  contains 
potassium  silicate  instead  of  sodium  silicate.  It  is  not  as 
readily  attacked  by  water,  acids,  and  alkalies  as  soda  lime 
glass,  and  hence  is  used  for  making  glassware  for  chemical 
purposes,  like  beakers,  retorts,  etc.  Crown  glass  is  also  a 
potash  lime  glass.  Jena  glass  contains  boric  anhydride. 
Blue  glass  is  colored  by  cobalt  oxide ;  brown  glass  by  ferric 
oxide ;  green  glass  by  ferrous  oxide  or  chromic  oxide ;  etc. 
Black  glass  contains  large  amounts  of  iron  and  other  metallic 
oxides.  Milk  glass  contains  suspended  particles  of  calcium 


136  CHEMISTRY  AND   DAILY  LIFE 

phosphate.  The  Egyptians  and  Phoenicians  knew  how  to 
make  glass  long  before  the  Christian  era.  Window  glass  was 
first  used  in  the  sixteenth  century. 

Metallic  magnesium  is  sold  in  the  market  in  powder,  and 
in  the  form  of  wire  or  ribbon.  It  burns  with  a  brilliant  white 
light,  forming  magnesium  oxide,  MgO.  The  metal  is  used  for 
fireworks,  for  flash  lights  in  signalling  and  in  photography. 


FIG.  44.  —  Manufacture  of  glass.    Rolling  out  plate  glass. 

Five  parts  of  magnesium  powder  to  nine  parts  of  pulverized 
potassium  chlorate  makes  a  good  flash-light  powder. 

In  nature  magnesium  is  found  as  magnesite,  the  carbonate 
MgCO3,  but  far  more  commonly  as  dolomite  or  magnesium 
limestone,  MgCO3 .  CaCO3,  which  has  already  received  men- 
tion. Magnesium  occurs  in  many  natural  silicates  very 
widely  distributed.  So  there  are  hornblende  Mg2CaFeSi4Oi2, 
asbestos  Mg3Si2O7 . 2  H2O,  meerschaum  Mg2Si3O8 . 4  H2O, 
and  many  other  complex  silicates  that  contain  magnesium. 
All  plants  and  animals  contain  magnesium  compounds,  and 


THE   METALS  OF  THE  ALKALIES  137 

these  finally  appear  in  the  ash  as  phosphates  and  carbonates. 
Magnesium  ammonium  phosphate  occurs  in  guano  and  is 
valuable  as  a  fertilizer. 

Magnesium  oxide  and  magnesium  carbonate  are  used  in 
medicine.  The  latter  compound  also  serves  as  a  face  powder. 
Talc,  a  hydrous  magnesium  silicate,  is  used  for  the  same  pur- 
pose. Magnesium  sulphate  serves  as  a  purgative  under  the 
name  Epsom  salt.  A II  magnesium  salts  have  a  bitter  taste  and 
act  as  laxatives.  When  found  in  natural  waters,  the  latter 
are  called  bitter  waters.  Some  of  them,  like  the  waters  of  the 
springs  at  Epsom  in  England  and  Hunyad  in  Hungary,  are 
quite  famous.  It  is  to  be  borne  in  mind  that  while  the  car- 
bonates and  phosphates  of  barium,  strontium,  calcium,  and 
magnesium  are  difficultly  soluble  in  water,  and  the  sulphate  of 
barium  is  insoluble,  the  sulphates  of  strontium  and  calcium 
are  sparingly  soluble,  the  sulphate  of  magnesium  is  quite 
readily  soluble.  Four  parts  of  water  dissolve  one  part  of  mag- 
nesium sulphate  crystals  at  room  temperatures. 

In  their  chemical  behavior,  magnesium  compounds  are  in 
many  ways  analogous  to  those  of  zinc. 

Magnesium  chloride,  which  is  cheap,  as  it  is  a  by-product 
of  the  potash  salt  industry  at  Stassfurt,  forms  with  mag- 
nesium oxide  a  basic  magnesium  chloride.  This  sets  as 
a  hard  mass,  and  is  frequently  used  as  a  cement  in 
making  floors,  wainscoting,  etc.  The  oxide  obtained  by 
calcining  native  magnesium  carbonate  is  mixed  dry  with 
the  appropriate  amount  of  sand,  sawdust,  or  other  filler 
and  the  desired  pigment,  and  then  this  powder  is  treated 
with  magnesium  chloride  solution  of  proper  strength,  as  in 
making  a  mortar.  The  material  is  spread  out  with  trowels, 
and  sets  in  about  24  to  30  hours  to  a  hard  mass  of  good 
wearing  qualities.  In  Germany  the  material  is  called 
"  Stemholz."  In  America  this  cement  is  being  intro- 


138  CHEMISTRY  AND  DAILY  LIFE 

duced,    and   various   fanciful   trade   names   are   being  ap- 
plied to  it. 

The  salts  of  the  element  radium  are  similar  to  those  of  the 
metals  of  the  alkaline  earths.  Radium  salts  glow  in  the  dark. 
The  light  affects  photographic  plates.  The  intensity  of  this 
light  increases  with  the  purity  of  the  radium  compounds. 
Heat  is  also  constantly  evolved  by  radium  compounds,  and  the 
air  in  their  immediate  neighborhood  has  less  electrical  resistance 
than  ordinary  air.  This  is  due  to  the  radiations  or  so-called 
emanations  that  are  continually  being  emitted  by  radium 
compounds.  In  extremely  minute  amounts,  which  indeed 
are  almost  infinitesimal,  radium  compounds  are  very  widely 
distributed  in  soils  and  natural  waters.  In  uranium  com- 
pounds, especially  in  an  oxide  of  uranium  known  as  pitch- 
blende, radium  occurs  in  relatively  larger  quantities.  The 
emanations  from  radium  are  able  to  destroy  germs.  They  also 
stop  the  germinating  power  of  seeds  and  kill  the  tissues  of  living 
beings.  Experiments  with  radium  compounds  must  there- 
fore be  conducted  with  great  care.  Their  value  as  an  agent 
for  curing  diseases  is  still  a  question  to  be  determined. 

QUESTIONS 

1.  Name  the  alkali  metals  and  state  their  general  characteristics. 

2.  What  is  potash  and  how  is  caustic  potash  prepared  from  it  ? 

3.  Where  is  potassium  found  in  nature  ? 

4.  Mention  five  important  compounds  of  potassium. 
6.  What  is  black  gunpowder  chemically  ? 

6.  How  is  potassium  chlorate  made,  and  what  is  it  used  for  ? 

7.  What  is  potassium  cyanide?    What  are  its  properties  and 
uses? 

8.  How  may  sodium  compounds  be  distinguished  from  potas- 
sium compounds? 

9.  Where  is  common  salt  found  in  nature  ?    What  is  salt  used  for  ? 


THE   METALS  OF  THE   ALKALIES  139 

10.  What  are  the  two  processes  for  making  soda  on  a  commercial 
scale  ?    What  uses  are  made  of  soda  ? 

11.  What  is  the  difference  between  washing  soda  and  baking 
soda? 

12.  (a)  What  is  Glauber's  salt?     (6)  What  is  the  "hypo"  used 
in  photography  ?     (c)  What  is  sodium  water  glass,  and  for  what  is 
it  used  ? 

13.  Name  the  metals  of  the  alkaline  earths  and  state  why  they 
are  so  called. 

14.  What  is  barium  sulphate  ?    What  is  it  used  for  ?    By  what 
other  names  is  it  known  ? 

16.  How  much  barium  is  there  in  a  ton  of  barium  sulphate  ? 

16.  What  use  is  made  of  strontium  nitrate  ? 

17.  What  are  the  various  forms  in  which  calcium  carbonate 
occurs?    How  do  we  know  that  these  are  all  one  and  the  same 
chemically.? 

18.  What  is  gypsum  ?    Plaster  of  Paris  ? 

19.  What  happens  when  plaster  of  Paris  sets  ? 

20.  Explain  the  action  of  hydrochloric  acid  on  limestone. 

21.  Of  what  value  is  calcium  nitrate  in  soils  ? 

22.  What  is  phosphate  rock  and  why  is  it  valuable  ? 

23.  How  is  Portland  cement  made  ? 

24.  What  is  " natural  cement"  ?    Where  is  it  made ? 
26.  What  are  the  uses  of  Portland  cement  ? 

26.  What  is  common  glass  chemically?    How  does  soft  glass 
differ  chemically  from  hard  glass  ?    How  is  colored  glass  produced  ? 
When  was  window  glass  first  made  ? 

27.  For  what  purposes  is  metallic  magnesium  used  ? 

28.  Mention  five  compounds  of  magnesium  that  occur  in  nature. 

29.  What  is  Epsom  salt  chemically  ? 

30.  Mention  some  of  the  characteristics  of  compounds  of  radium. 


CHAPTER   XI 


ALUMINUM,   THE    HEAVY   METALS,   AND   THEIR 
IMPORTANT    ALLOYS 

OF  all  the  metals  aluminum  is  by  far  the  most  abundant, 
forming  about  8  per  cent  of  the  material  of  which  the  earth's 
crust  is  composed.  It  is  found  mainly  as  a  constituent  of  all 

the  common  siliceous 
rocks,  especially  in  feld- 
spars, clays,  micas,  gran- 
ites, slates,  etc.  It  never 
occurs  in  the  uncombined 
state,  for  it  has  great  affin- 
ity for  oxygen,  and  in- 
deed it  nearly  always  is 
found  in  compounds  with 
that  element.  Emery  is 
an  impure  form  of  alu- 
minum oxide,  being 
colored  brown  by  the 
presence  of  oxides  of  iron. 
Sapphires  and  rubies  are 
beautifully  crystallized 
aluminum  oxide  and  are 
highly  prized  as  gems. 
Bauxite  is  a  hydrated  ox- 
ide of  aluminum,  and  is 
used  as  a  source  for  the 
manufacture  of  alumi- 
140 


FIG.  45.  — An  emery  wheel. 


ALUMINUM,   HEAVY  METALS,   ALLOYS          141 

num.  In  Greenland  a  double  fluoride  of  sodium  and  alumi- 
num, A1F3 .  3  NaF,  is  found.  It  forms  white  masses  insoluble 
in  water.  This  mineral  is  called  cryolite.  It  may  be  melted 
quite  readily  and  the  molten  mass  dissolves  aluminum  oxide. 
By  passing  the  electric  current  through  this  molten  mass 
metallic  aluminum  is  deposited  and  oxygen  comes  off  at  the 
other  pole.  The  bath  is  replenished  by  continually  feeding 
in  more  aluminum  oxide,  also  called  alumina.  The  molten 
mass  is  contained  in  a  vessel  of  graphitic  carbon  which  serves 


FIG.  46.  —  Cooking  utensils  made  of  aluminum. 

as  the  pole  on  which  the  metal  is  deposited.  Carbon  sticks 
dipped  into  the  molten  mass  form  the  other  pole.  Eight 
volts  electrical  pressure  is  sufficient  to  keep  the  process  going, 
but  the  current  strength  is  usually  several  thousand  amperes. 
Thus  the  heat  developed  by  the  electric  current  is  itself  sufficient 
to  keep  the  bath  and  the  deposited  metal  as  well  in  the  molten 


142  CHEMISTRY  AND  DAILY  LIFE 

state,  once  the  process  has  been  started.  The  molten  alu- 
minum is  tapped  off  from  the  bottom  of  the  vessel  from  time 
to  time.  Over  twenty-five  thousand  tons  of  aluminum  are  thus 
produced  annually  in  the  United  States  alone.  The  metal 
sells  for  less  than  twenty  cents  per  pound.  Aluminum  metal 
is  silver-white  in  appearance,  though  on  exposure  to  the  air 
it  oxidizes  slowly,  and  the  film  of  oxide  on  its  surface  gives  the 
metal  a  bluish  appearance.  Aluminum  is  only  about  one- 
third  as  heavy  as  iron.  It  is  malleable,  ductile,  melts  at 
660°,  and  is  a  good  conductor  of  electricity  and  also  of  heat. 
It  is  used  for  wires  and  electric  cables,  for  cooking  utensils, 
and  many  other  useful  articles. 

Magnalium  is  an  alloy  consisting  of  75  to  90  per  cent  of 
aluminum  and  25  to  10  per  cent  magnesium.  It  is  harder  and 
lighter  than  aluminum  and  may  be  polished  to  a  higher  degree. 
Aluminum  bronze  consists  of  90  to  95  per  cent  copper  and  10 
to  5  per  cent  aluminum.  It  is  yellow  in  color,  hard  and 
strong,  and  is  consequently  often  used  in  the  arts. 

Aluminum  paint  consists  of  finely  divided  aluminum  sus- 
pended in  a  suitable  varnish  or  laquer. 

Mixed  with  the  black  oxide  of  iron,  Fe3O4,  finely  divided 
metallic  aluminum  forms  a  mixture  called  thermite.  When 
once  this  mixture  is  ignited  (which  can  be  accomplished  by 
means  of  a  fuse  of  magnesium  ribbon  to  which  is  attached  a 
mixture  of  magnesium  powder  and  potassium  chlorate) 
the  chemical  action  continues  rapidly  and  vigorously,  the 
temperature  developed  being  about  3000°  C.  The  change 
that  takes  place  is  that  aluminum  robs  the  oxide  of  iron  of  its 
oxygen  and  so  forms  alumina  and  metallic  iron,  thus : 

3Fe3O4        +       8A1        =     4  A12O3      +       9  Fe 

black  iron  oxide  aluminum  alumina  iron 

Thermite  is  used  for  welding  car  rails  and  making  welds   in 


ALUMINUM,   HEAVY  METALS,  ALLOYS          143 

many  parts  of  machinery  of  various  kinds.  The  parts  need 
only  to  be  butted  together,  a  mold  built  around  the  joint, 
and  the  molten  thermite  mixture  run  upon  it.  Thus  the  iron 
is  heated  to  the  welding  point  very  quickly.  In  many  cases 


FIG.  47.  —  Welding  a  car  rail  with  thermite. 

it  is  not  even  necessary  to  take  the  machinery  apart  to  make 
the  repairs,  the  process  is  so  simple. 

Aluminum  sulphate,  A12(SO4)3,  is  made  by  dissolving  alu- 
minum hydroxide,  A1(OH)3,  in  sulphuric  acid,  thus : 
2  A1(OH)3  +  3  H2SO4  =  A12(SO4)3  +  6  H2O 
This  salt  is  readily  soluble  in  water  and  is  used  as  a  mordant 
for  fixing  dyestuffs  upon  fabrics.     In  the  paper  industry  it 
serves  in  sizing  paper. 

Ordinary  potassium  alum  is  a  double  sulphate  of  aluminum 
and  potassium.  It  has  the  composition  K2SO4 .  A12(SO4)3 . 
24  H2O.  Ammonium  alum  and  sodium  alum  contain  am- 
monium and  sodium  respectively  instead  of  potassium, 
otherwise  they  are  quite  like  potassium  alum.  Alum  crystal- 


144  CHEMISTRY  AND   DAILY  LIFE 

lizes  in  octahedra,  dissolves  readily  in  water,  and  like  all 
other  soluble  aluminum  salts,  it  has  an  astringent  effect  on  the 
mucous  membranes.  Alum  is  used  as  a  mouth  wash  in  medi- 
cine, as  a  mordant  in  dyeing  fabrics,  and  unfortunately  it  is 
also  still  used  in  baking  powders.  Alum  baking  powders 
contain  alum  or  aluminum  sulphate  and  baking  soda.  When 
this  mixture  is  moistened,  as,  for  example,  in  baking,  carbon 
dioxide  is  evolved  which  raises  the  dough.  There  is  simul- 
taneously formed  sodium  sulphate  and  aluminum  hydroxide, 
and  these  remain  in  the  biscuit,  bread,  or  cake.  The  alumi- 
num hydroxide  is  readily  dissolved  by  the  hydrochloric  acid 
in  the  stomach,  thus  forming  aluminum  chloride,  a  powerful 
astringent  which  interferes  with  digestion  and  is  harmful  to 
the  linings  of  the  digestive  tract.  Bread  and  cake  made  with 
alum  baking  powder  looks  well,  for  the  carbon  dioxide  is 
liberated  steadily  and  just  about  at  the  right  rate  to  make 
fine-appearing  cookery.  As  alum  baking  powders  are  cheap 
they -are  still  unfortunately  much  in  use,  even  though  in  some 
states  the  law  requires  the  fact  that  they  contain  alum  or 
aluminum  sulphate  to  be  stated  on  the  label  to  warn  the 
public. 

It  is  a  notable  fact  that  though  aluminum  silicates  are  present 
in  every  soil,  plants  and  animals  only  contain  minute  traces  of 
aluminum. 

Clay  consists  essentially  of  aluminum  silicates  that  have 
been  formed  from  the  weathering  of  feldspars  and  other 
complex  silicates  that  make  up  the  granitic  rocks.  In  its 
purest  form  clay  is  white  and  is  called  kaolin,  H2Al2(SiO4)2 . 
2  H2O.  This  is  used  for  making  white  porcelain  ware. 
Common  clay  is  discolored  by  impurities.  Usually  it  is  brown 
or  red,  which  is  caused  by  the  presence  of  oxides  of  iron. 
Ordinary  clay  serves  for  making  bricks,  flowerpots,  and  the 
inferior  and  cheaper  grades  of  pottery  and  crockery  ware. 


ALUMINUM,   HEAVY    METALS,   ALLOYS         145 

In  making  bricks  and  porous  earthenware  the  clay  is  molded 
into  the  desired  shapes  and  then  heated  to  redness  in  kilns, 
or  "  fired  "  as  it  is  called.  A  cheap  glaze  may  be  put  upon 
such  ware  by  simply  throwing  salt  into  the  kiln.  Thus  as  the 
water  is  baked  out  of  the  clay,  the  water  vapor  at  the  high 
temperature  that  obtains  decomposes  the  salt,  forming  hydro- 
chloric acid  and  sodium  hydroxide.  The  latter  unites  with 
the  surface  of  the  clay,  forming  an  easily  fusible  silicate  which 


FIG.  48.  — A  pottery  kiln.     Setting  the  shapes  and  getting  ready  to  fire. 

produces  a  thin  glassy  coating  or  so-called  glaze.  Butter 
jars  and  other  "  stoneware  "  crocks  are  glazed  in  this  way. 
Porcelain  is  vitreous  throughout.  This  is  accomplished  by 
mixing  finely  pulverized  feldspar  and  quartz  with  the  kaolin 
before  molding  the  dishes.  When  these  are  dried  and  finally 
fired,  the  feldspar  and  quartz  fuse  and  fill  the  pores  of  the 
ware  so  that  it  exhibits  a  perfectly  vitreous  fracture  instead 
of  an  earthy  one,  as  the  cheaper  earthenware,  either  glazed  or 


146  CHEMISTRY  AND   DAILY  LIFE 

unglazed,  always  does.  Fire  bricks  contain  a  larger  amount 
of  silica  than  ordinary  ones  and  are  consequently  more 
refractory.  Fire  clay  also  is  especially  rich  in  silica.  Colored 
porcelain  and  colored  glazes  are  produced  by  means  of  various 
metallic  oxides,  as  in  making  colored  glass,  for  example. 

Ultramarine  is  a  fine  dark  blue  pigment  made  by  heating 
together  clay,  soda,  sulphur,  and  charcoal  out  of  contact  with 
the  air.  It  is  probably  a  double  compound  of  sodium  alu- 
minum silicate  and  sodium  sulphide.  Ultramarine  is  attacked 
by  acids,  which  destroy  its  color,  but  in  presence  of  alkalies 
it  is  quite  stable.  It  serves  as  laundry  blue,  also  as  a  pigment 
in  paints,  and  in  the  manufacture  of  wall  paper.  Further- 
more, it  is  used  to  destroy  the  yellow  appearance  of  sugar, 
linen,  cotton,  and  paper  pulp,  only  enough  being  used  to  pro- 
duce a  pure  white  appearance. 

Aluminum  oxide,  being  a  white  powder  that  is  practically 
insoluble  in  water  and  neutral  in  reaction  toward  litmus,  is  a 
typical  "  earthy  "  oxide,  and  aluminum  is  therefore  termed  an 
earth  metal.  There  are  several  other  similar  earth  metals, 
but  they  are  so  very  rare  and  have  no  importance  in  practice 
that  they  need  not  be  considered  here.  The  oxides  of  cerium 
and  thorium  belong  to  these  rare  earths.  It  has  already 
been  stated  that  these  are  used  in  making  mantles  for  the 
Welsbach  lamps.  In  the  Nernst  lamp  a  filament  of  earthy 
oxides  is  heated  to  incandescence  by  passing  the  electric 
current  through  it. 

Platinum,  gold,  and  silver  are  called  the  noble  metals.  They 
occur  in  nature  in  the  free  or  uncombined  state  and  are  not 
at  all  readily  oxidized. 

Platinum  is  silver-white,  very  malleable,  and  ductile.  It 
occurs  in  alluvial  sands  in  the  Ural  Mountains,  in  California, 
Brazil,  and  Australia.  It  is  not  attacked  by  hydrochloric, 
nitric,  or  sulphuric  acid,  nor  by  molten  sodium  or  potassium 


ALUMINUM,   HEAVY   METALS,   ALLOYS          147 

carbonate,  though  aqua  regia,  a  mixture  of  nitric  and  hydro- 

chloric acid,  will  dissolve  it,  forming  platinic  chloride.     Plat- 

inum does  not  melt  readily,  its  melting  point  being  about 

1777°.     These  facts  make  it  very  valuable  as  a  material 

out  of  which  to  construct  dishes  for  certain  kinds  of  chemical 

work  in  which  glass  and  porcelain  would  be 

attacked.     Platinum  is  also   used  for  electri- 

cal contacts  and  for  spark  points  in  the  spark 

plugs    of    gasoline    engines.      For    the    latter 

purpose  it  is  commonly  alloyed  with  indium, 

a  metal  which  is  similar  to  platinum.     This 

alloy  is  the  so-called  hard  platinum.     Plati- 

num salts  are  used  in  photography,  and  also 

in   chemistry   for  the  purpose   of   estimating 

potassium,    for    potassium    platinic    chloride, 

K2PtCl6,  is  a  beautiful,  crystalline,  yellow  salt 

which  is  difficultly  soluble  in  dilute  alcohol. 

It  is   one   of   the    very   few   potassium   salts  F  I  G  •  4  9  •      A 

.  modern  spark 

that  do  not  dissolve  copiously  in  water.     In      piug     with 


a  finely  divided  form  platinum  absorbs  oxy- 
gen  which  is  readily  given  off  to  oxidizable  sub- 
stances. So,  for  example,  one  can  light  a  gas  jet  by 
bringing  it  into  contact  with  such  finely  divided  plati- 
num, also  called  platinum  sponge.  Other  metals  of  the 
platinum  family  are  iridium,  osmium,  ruthenium,  rho- 
dium, and  palladium.  They  all  occur  with  platinum  in 
nature  and  exhibit  somewhat  similar  properties.  The  many 
uses  to  which  platinum  has  been  put  and  the  small  supply 
make  the  metal  very  costly.  It  is  worth  about  forty-five 
dollars  per  ounce. 

Gold,  aurum,  has  always  been  regarded  as  an  article  of 
value.  It  melts  at  1064°,  is  extremely  malleable  and  ductile. 
In  aqua  regia  it  dissolves,  forming  gold  chloride.  Gold  coins 


148  CHEMISTRY  AND    DAILY   LIFE 

contain  9  parts  gold  and  1  part  copper.  This  alloy  is  much 
harder  than  pure  gold,  which  is  rather  soft  and  consequently 
will  not  wear  well.  For  the  same  reason  copper  alloys  of 
gold  are  used  for  jewelry,  ornaments,  etc.  Pure  gold  is 
24  carats  fine ;  16  carat  gold  contains  16  parts  gold  and  8 
parts  copper;  14  carat  gold  contains  14  parts  gold  and  10 
parts  copper;  etc.  The  LTnited  States  produces  about  160 
tons  of  gold  annually,  valued  at  about  $96,500,000.  The 
whole  world  produces  about  four  times  this  amount  per  year. 
Gold  salts  are  used  in  photography  as  "  toning  baths." 
Many  metallic  articles  are  plated  with  gold.  This  is  accom- 
plished by  immersing  the  article  to  be  plated  in  a  bath  con- 
sisting of  a  solution  of  gold  potassium  cyanide,  KAu(CN)4, 
together  with  an  electrode  of  pure  gold ;  a  current  of  electric- 
ity is  then  passed  from  the  latter  electrode  through  the  solu- 
tion to  the  article  to  be  plated,  which  is  readily  coated  with 
the  metal.  Gold  is  also  used  on  the  edges  and  backs  of  books, 
for  ornamenting  chinaware,  gilding  signs,  church  spires,  etc. 

Silver,  argentum,  occurs  in  nature  in  the  free  state,  but  also 
as  the  sulphide  and  chloride.  It  is  much  more  abundant  than 
platinum  and  gold.  Nearly  2000  tons  of  silver  are  produced 
annually  in  the  United  States.  The  metal  melts  at  962°,  is 
malleable,  ductile,  and  the  best  conductor  of  electricity  and  heat 
known.  Sterling  silver  and  silver  coins  contain  1  part  cop- 
per and  9  parts  silver.  Nitric  acid  dissolves  silver  readily, 
forming  silver  nitrate,  AgNOs,  which  is  the  most  important  of 
the  silver  compounds,  for  from  it  all  others  are  prepared.  It  is 
used  in  medicine  and  in  photography.  It  is  one  of  the  most 
soluble  of  all  salts.  Even  in  ice-cold  water  it  is  possible  to 
dissolve  122  parts  in  100  parts  of  water,  while  in  boiling 
water  the  solubility  increases  tenfold.  This  salt  is  also  called 
lunar  caustic  and  is  used  for  cauterizing  wounds,  removing 
warts,  etc.  Silver  chloride,  AgCl,  silver  bromide,  AgBr,  and 


ALUMINUM,   HEAVY  METALS,   ALLOYS          149 

silver  iodide,  Agl,  are  all  insoluble  in  water.  These  salts 
darken  on  exposure  to  light,  probably  because  of  separation  of 
finely  divided  silver.  This  fact  is  the  basis  of  the  use  of  these 
salts  in  photography.  The  photographic  plate  consists 


(B) 
FIG.  50. — Photography.     (A)  A  positive.     (B)  A  negative. 

tially  of  silver  bromide  embedded  in  gelatine,  which  covers 
one  side  of  the  glass.  On  exposure  to  light  in  the  camera, 
the  bromide  is  slightly,  but  not  visibly,  reduced.  When 
the  plate  is  afterwards  treated  with  a  developer  (a  reducing 
agent  like  pyrogallic  acid,  hydrochinone,  etc.),  the  reduction 
continues  where  the  light  has  started  it,  and  so  the  picture 
becomes  visible.  The  developer  must  be  washed  off  when  the 


150  CHEMISTRY  AND   DAILY   LIFE 

picture  has  been  sharply  developed  or  the  process  will  continue 
and  produce  a  blurred  outline.  To  remove  the  undecom- 
posed  silver  bromide  in  the  gelatine,  the  plate  (before  expo- 
sure to  light)  must  be  treated  with  a  solution  of  sodium 
thiosulphate,  Na^Os,  the  "  hypo  "  bath.  This  dissolves 
the  silver  bromide,  leaving  only  the  gelatine  with  the  metallic 
silver  particles  which  form  .the  outline  of  the  picture.  The 
plate  is  then  thoroughly  rinsed  off  and  dried.  It  is  a  nega- 
tive, i.e.  it  is  dark  where  the  object  which  was  photographed 
was  light,  and  vice  versa.  To  make  a  positive  this  negative 
is  laid  upon  a  bromide  print  paper,  which  is  paper  coated  with 
a  sensitive  film  of  silver  bromide  similar  to  that  on  the  bro- 
mide plate.  The  whole  is  now  exposed  to  the  light.  The 
print  must  be  "  fixed  "  in  the  "  hypo  "  bath  the  same  as  the 
negative,  and  it  may  then  be  exposed  to  the  light. 

Silver  plating  is  done  in  a  solution  of  potassium  silver 
cyanide,  KAg(CN)2.  The  process  is  similar  in  all  respects 
to  gold  plating,  which  has  already  been  mentioned.  The 
black  stains  that  form  on  silverware  (especially  on  spoons, 
forks,  etc.,  which  have  been  in  contact  with  eggs)  are  silver 
sulphide,  and  not  silver  oxide  as  is  often  thought. 

Copper,  cuprum,  occurs  in  large  quantities  in  the  free  state 
near  Lake  Superior.  In  Montana  it  is  found  in  ores  in 
combination  with  iron  and  sulphur.  Nearly  half  of  the  an- 
nual output  of  copper  in  the  world  is  produced  in  the  United 
'States,  which  contributes  about  540,000  tons  per  year.  Copper 
and  gold  are  the  only  colored  metals  known.  Copper  melts 
at  1084°.  It  is  tough,  rather  hard,  ductile,  and  malleable. 
It  conducts  heat  and  electricity  well.  Much  copper  wire  is 
used  in  electrical  work.  For  other  purposes,  however,  copper 
is  generally  used  in  the  form  of  alloys.  These  are  made  by 
melting  the  metals  together  in  the  desired  proportions. 
The  following  are  some  of  the  most  important  alloys  of 


ALUMINUM,   HEAVY  METALS.   ALLOYS         151 


FIG.  51.  —  Plating  silver  spoons.    The  upper  figure  shows  the  rack  on  which 
the  spoons  are  hung. 


152  CHEMISTRY  AND  DAILY  LIFE 

copper :  Brass,  which  is  yellow  in  color,  contains  1  part 
zinc  and  2  parts  copper,  though  other  proportions  are  often 
used.  Dutch  metal,  which  is  reddish  brown,  consists  of 
1  part  zinc  and  5  parts  copper.  German  silver  consists  of 
80  to  95  per  cent  brass  and  5  to  10  per  cent  nickel.  Gun 
metal  contains  9  parts  copper  in  1  part  tin.  Bell  metal 
consists  of  3  parts  copper  plus  1  part  tin.  The  alloys  of 
copper  and  tin  are  called  bronzes.  Bronzes  for  statuary  com- 
monly contain  3  to  8  parts  tin,  1  to  3  parts  lead,  1  to  10  parts 
zinc,  and  80  to  90  parts  copper.  Phosphor  bronze  is  used 
in  making  parts  of  machinery.  It  is  especially  hard.  It 
consists  of  bronze  to  which  from  0.5  to  3  per  cent  phosphorus 
has  been  added.  Copper  dissolves  readily  in  nitric  acid,  also 
in  hot  concentrated  sulphuric  acid,  but  cold  sulphuric  or 
hydrochloric  acid  has  but  very  little  effect  on  it.  However, 
in  presence  of  the  air,  many  dilute  acids  do  very  gradually 
attack  copper,  which  fact  must  be  kept  in  mind,  for  copper 
and  brass  are  frequently  used  for  cooking  utensils,  and  copper 
compounds  are  poisonom.  On  copper  roofs,  old  coins,  etc., 
that  have  been  exposed  to  moist  air  for  a  long  time  there  is 
formed  a  green  deposit  called  verdigris.  It  is  a  basic  carbon- 
ate of  copper,  CuCO3 .  Cu(OH)2.  In  ammonia  water  copper 
is  soluble  when  in  contact  with  the  oxygen  of  the  air.  However, 
ammonia  acts  but  slowly,  hence  it  is  often  used  for  cleaning 
copper.  The  most  important  as  well  as  the  most  common  salt 
of  copper  is  copper  sulphate,  blue  vitriol,  CuSCX .  5  H2O.  It 
forms  large  blue  crystals,  is  soluble  in  about  3  parts  of  water, 
and  its  solutions  are  used  as  a  bath  for  copper  plating,  for 
spraying  plants,  especially  in  making  Bordeaux  mixture,  and 
also  for  preparing  other  copper  compounds.  In  Paris  green 
copper  also  is  present,  as  has  been  mentioned  before. 

Mercury,    quicksilver,   hydrargyrum,   is   the   only   metal 
which  is  a  liquid  at  ordinary  temperatures.     It  is  found  in 


ALUMINUM,   HEAVY  METALS,   ALLOYS         153 

nature  in  the  free  state,  but  generally  it  is  combined  with 
cinnabar,  HgS,  which  is  red  in  color  and  is  used  as  a  pigment, 
being  called  vermilion.  Mercury  comes  from  Spain,  Austria, 
Prussia,  California,  Japan,  and  China.  It  is  used  in  ther- 
mometers, barometers,  in  amalgams  for  the  backs  of  mirrors, 
also  for  filling  teeth.  Its  compounds  are  used  in  medicine. 
So  mercurous  chloride,  HgCl,  is  calomel.  It  is  but  slight'y 
soluble  in  water.  Mercuric  chloride,  HgCl2,  is  corrosive 
sublimate.  It  is  very  copiously  soluble  in  water  and  is  an 
exceedingly  powerful  poison.  It  is  to  be  borne  in  mind,  more- 
over, that  all  mercury  compounds  are  poisonous.  The  antidote 
is  raw  eggs  and  milk.  The  albumin  forms  an  insoluble  com- 
pound with  the  mercury  salt,  which  is  then  got  rid  of  by  an 
emetic  or  a  purge.  Mercury  melts  at  —  39°.4  C.  and  boils  at 
357°  C.  Solid  mercury  may  be  hammered  into  sheets  and 
cut  with  tools  like  other  metals.  The  alloys  of  mercury  with 
other  metals  are  called  amalgams.  The  amalgam  used  in 
filling  teeth  commonly  consists  of  tin,  silver,  and  mercury. 
Gold  alloys  very  readily  with  mercury.  Indeed,  the  latter 
readily  dissolves  gold,  and  so  is  used  in  extracting  fine  particles 
of  gold  from  the  sands  in  which  they  occur.  Mercury  is  also 
similarly  used  in  silver  mining. 

Tin,  stannum,  occurs  in  nature  as  tinstone,  cassiterite, 
SnO2,  which  is  found  in  England,  Germany,  Peru,  Australia, 
Banca,  and  Alaska.  To  obtain  the  tin  from  this  ore,  the 
latter  is  heated  with  carbon,  thus  : 

SnO2  +  2  C  =  2  CO  +  Sn. 

Tin  is  very  malleable,  melts  at  232°,  and  boils  at  1600°.  On 
exposure  to  the  air  tin  remains  nearly  unchanged.  It  is  used 
in  making  tin  foil  and  tin  plate.  The  latter  consists  of  sheet 
iron  coated  with  tin  by  the  process  of  dipping  the  thoroughly 
cleaned  iron  into  a  bath  of  molten  tin.  Frequently  copper 
is  also  treated  by  this  method.  Metallic  tin  is  also  used  in 


154  CHEMISTRY  AND  DAILY  LIFE 

many  alloys.  Thus  solder  commonly  consists  of  1  part  tin 
and  1  part  lead,  though  other  proportions  are  also  employed. 
The  bronzes,  already  mentioned,  are  alloys  of  tin  and  copper. 
Pewter  consists  of  1  part  lead  and  3  parts  tin.  Britannia 
metal  contains  90  per  cent  tin,  8  per  cent  antimony,  and  2 
per  cent  copper.  Among  the  most  important  salts  of  tin  are 
stannous  chloride,  SnCl2,  formed  by  dissolving  tin  in  hot 
concentrated  hydrochloric  acid  solution,  and  stannic  chloride, 
SnCl4,  produced  by  treating  tin  or  stannous  chloride  with 
chlorine.  Stannous  chloride  forms  white  crystals  that  are 
very  soluble  in  water,  while  stannic  chloride  is  a  fuming  liquid 
which  boils  at  114°.  With  ammonium  chloride  stannic 
chloride  forms  a  double  salt,  SnCl4  .  NH4C1,  called  pink  salt, 
which  is  used  as  a  mordanto  Stannous  chloride  is  a  reducing 
agent,  for  it  readily  passes  over  into  stannic  chloride,  for 
example ; 

SnCl2    +    HgCl2     =    SnCl4    +    Hg 

stannous  mercuric  stannic          mercury 

chloride  chloride  chloride 

Mosaic  gold  is  stannic  sulphide,  SnS2,  prepared  by  heating 
together  sulphur  and  tin.  It  consists  of  golden  yellow  crys- 
tals, and  is  used  for  "  bronzing  "  articles.  Tin  is  a  rather 
costly  metal.  The  world  produces  about  110,000  tons  of  it 
annually.  Most  of  this  is  mined  in  Banca  and  other  neigh- 
boring East  India  islands. 

Lead,  plumbum,  is  soft  and  malleable.  It  melts  at  327°  C. 
and  it  is  11.4  times  heavier  than  water.  This  metal  has  been 
used  in  the  arts  even  in  ancient  times.  The  Romans  used 
lead  for  water  pipes,  and  it  serves  for  this  purpose  to  this 
day.  The  chief  ore  of  lead  is  the  sulphide  PbS,  which  crystal- 
lizes in  cubes.  It  is  commonly  known  as  galenite.  As 
already  mentioned,  solder  and  pewter  are  alloys  of  lead  and 
tin.  Shot  and  bullets  consist  of  lead  containing  about  three- 


ALUMINUM,   HEAVY  METALS,   ALLOYS          155 


tenths  per  cent  arsenic,  while  in  Babbitt  metal  from  70  to 
90  per  cent  lead  is  alloyed  with  antimony  and  tin.  Much 
lead  is  used  also  in  the  manufacture  of  lead  storage  batteries 
and  in  making  lead  salts  and  other  compounds.  The  lead 
storage  battery  consists  essentially  of  a  lead  plate  and  a  lead 
plate  coated  with  lead  peroxide, 
PbO2,  dipping  in  a  solution  of  sul- 
phuric acid  of  specific  gravity  1.2. 
As  the  battery  acts,  the  current 
flows  from  the  lead  through  the 
solution  to  the  lead  peroxide. 
Thus  lead  is  dissolved  and  hydro- 
gen is  set  free  at  the  other  plate, 
but  it  at  once  attacks  the  lead 
peroxide,  forming  lead  oxide  and 
water.  The  lead  oxide  formed  is 
dissolved  by  the  sulphuric  acid 
present,  forming  water  and  lead 
sulphate.  The  electromotive  force 
of  the  battery  is  two  volts.  Charg- 
ing the  battery  consists  simply  in 

conducting  a  current  from  a  dynamo  through  the  battery 
from  the  peroxide  plate  through  the  solution  to  the  lead  plate. 
Thus  lead  is  again  deposited  on  the  lead  plate  and  lead  per- 
oxide is  again  formed  on  the  opposite  plate ;  that  is  to  say, 
the  chemical  changes  that  took  place  when  the  battery  was 
discharged  are  reversed.  These  batteries  are  used  for  running 
electric  automobiles,  also  for  lighting  and  ignition  purposes, 
etc.,  for  they  have  a  high  electromotive  force  and  a  low  in- 
ternal resistance  and  so  yield  a  powerful  current. 

Litharge,  lead  oxide,  PbO,  is  a  yellow  powder  which  is  used 
extensively  in  glazing  pottery  and  ironware,  in  putting  decora- 
tions upon  porcelain,  and  in  making  glass  that  has  a  high  in- 


FIG.  52. — A  lead  storage  battery. 


156  CHEMISTRY  AND   DAILY   LIFE 

dex  of  refraction.  It  is  also  employed  in  making  various  lead 
salts.  The  most  common  soluble  lead  salts  are  the  nitrate, 
Pb(NO3)2,  and  the  acetate,  Pb(C2H3O2)2 .  3  H2O.  The  latter  is 
commonly  known  as  sugar  of  lead,  for  it  has  a  sweetish,  yet  dis- 
agreeable taste.  The  basic  lead  acetate,  Pb(C2H3O2)2 .  (PbO),, 
is  often  used  as  a  lotion  for  diseased  parts,  a  2  per  cent 
solution  of  this  salt  being  called  lead  water.  Lead  arsenate, 
Pb3(AsO4)2,  is  used  for  poisoning  potato  bugs  and  also  for 
spraying  trees  and  shrubs.  Like  Paris  green,  lead  arsenate 
is  but  sparingly  soluble  in  water.  White  lead  is  a  basic  car- 
bonate of  lead,  Pb(OH)2 .  2  PbCO3.  It  is  sold  in  large  quan- 
tities ground  in  linseed  oil.  On  being  further  diluted  with 
the  latter,  this  mixture  makes  an  excellent  paint,  especially 
for  wood  that  is  to  stand  exposure  to  the  weather.  White 
lead  paint  is  not  infrequently  adulterated  with  chalk,  so-called 
whiting,  barium  sulphate,  or  lead  sulphate.  It  is  to  be  borne 
in  mind  that  all  lead  compounds  are  poisonous.  The  more 
soluble  the  compounds  are,  the  greater  is  the  danger  of  being 
poisoned  by  means  of  them.  Painters  are  often  poisoned  by 
the  white  lead  they  use.  This  gets  on  their  hands,  and  it 
is  very  likely  that  when  these  touch  the  nose  and  lips,  the 
lead  compounds  come  into  contact  with  the  mucous  mem- 
branes and  are  absorbed.  Thus  small  quantities  are  taken 
into  the  system  at  a  time,  but  these  accumulate  and  finally 
cause  lead  colic. 

Chromium  is  a  hard,  steel-gray,  brittle  metal  which  melts 
at  about  1515°  C.  It  is  6.8  times  as  heavy  as  water.  It 
occurs  in  chrome  iron  ore,  Cr2O3 .  FeO,  and  is  used  in  making 
chrome  steel,  which  is  steel  alloyed  with  a  small  percentage 
of  chromium.  This  makes  a  very  hard  steel.  Chromic 
oxide,  Cr2O3,  is  chrome  green  and  is  used  as  a  pigment  in 
paint.  It  is  also  used  in  making  green  glass  and  glazes. 
Chrome  yellow  is  lead  chromate,  PbCrO4.  It  is  also  used  as  a 


ALUMINUM,   HEAVY  METALS,   ALLOYS          157 

pigment  in  paint.  The  most  common  soluble  compound  of 
chromium  is  potassium  bichromate,  K2Cr2O7.  It  forms 
beautiful  orange-colored  crystals.  It  semes  as  an  oxidizing 
agent,  also  in  chrome  tanning  and  in  dyeing  fabrics. 

Tungsten  is  also  a  brittle  metal.  In  some  of  its  properties 
it  resembles  chromium.  Tungsten  is  used  in  making  tungsten 
steel,  and  also  in  producing  the  filaments  for  the  incandescent 
tungsten  electric  lamps. 

Molybdenum  is  closely  allied  to  tungsten.  Ammonium 
molybdate,  (NH4)2MoO4,  is  used  in  testing  for  the  presence  of 
phosphates,  for  when  added  to  a  nitric  acid  solution  of  the  lat- 
ter there  forms  a  very  characteristic  yellow  precipitate  called 
ammonium  phosphomolybdate,  (NH^PCX  .  11  MoO3 .  6  H2O. 
This  precipitate  is  soluble  in  ammonia  water. 

Zinc  is  about  6.9  times  as  heavy  as  water,  melts  at  420°  C. 
and  boils  at  918°  C.  It  is  found  in  nature  mainly  as  the 
carbonate  ZnCO3,  and  the  sulphide  ZnS.  The  latter  ore  is 
popularly  known  as  blackjack.  These  ores  are  first  heated 
in  contact  with  the  air  and  are  thus  changed  to  zinc  oxide. 

ZnCO3     on  heating     =     ZnO      +      CO2 

zinc  carbonate  zinc  oxide      carbon  dioxide 

ZnS     +     30     =      ZnO     +      SO2 

zinc  sulphide        oxygen          zinc  oxide     sulphur  dioxide 
(from  the  air) 

From  its  oxide,  zinc  is  then  obtained  by  heating  with  carbon 
in  earthenware  retorts,  thus  : 

ZnO     +     C   =    Zn     +      CO 

zinc  oxide        carbon       zinc   ]   carbon  monoxide 

In  the  form  of  sheets  zinc  is  much  used  for  gutters,  roofs,  orna- 
ments, etc.,  on  buildings.  Galvanized  iron,  so  called,  consists 
of  sheet  iron  which  has  been  coated  with  zinc  by  the  process 
of  dipping  the  thoroughly  clean  iron  into  a  bath  of  molten 


158 


CHEMISTRY  AND   DAILY   LIFE 


FIG. 


53. — A  sal  ammoniac   battery, 
showing  the  parts. 


zinc.  The  beautiful  flaky  appearance  of  galvanized  iron  is 
due  to  the  crystals  of  zinc  on  its  surface.  The  coating  pro- 
tects the  iron  so  that  it  will  not  rust.  Zinc  is  also  used  in  many 

primary  electrical  batteries. 
In  the  common  battery  used 
for  ringing  doorbells,  Fig.  53, 
there  is  a  solution  of  ammo- 
nium chloride,  sal  ammoniac, 
into  which  dip  a  stick  of  zinc 
and'  a  cylindrical  plate  of 
carbon.  The  latter  is  usu- 
ally so  shaped  as  to  form  also 
the  cover  of  the  jar.  The 

battery  carbon  is  made  by  grinding  coke  with  black  strap 
molasses  or  coal  tar  as  a  binder,  molding,  and  then  heating  the 
product  at  first  gently,  and  finally  to  redness  out  of  contact 
with  the  air.  In  this  battery,  the  current  flows  from  the  zinc 
through  the  solution  to  the  carbon.  Zinc  chloride  is  thus 
formed  as  the  zinc  and  hydrogen  is  evolved  at  the  carbon. 
The  hydrogen  is  absorbed  by  the  carbon  and  finally  escapes  in 
the  air.  Dry  batteries  contain  the  same  in- 
gredients. Only  here  the  outer  casing  is  made 
of  zinc,  which  also  serves  as  the  negative  pole 
of  the  battery.  The  carbon  generally  is  a  cylin- 
drical piece  in  the  middle  of  the  cell  and  is  sur- 
rounded by  manganese  dioxide  which  oxidizes 
the  hydrogen  that  is  liberated.  Plaster  of 
Paris  is  used  to  absorb  the  liquid  and  hold  the 
ingredients  in  place.  But  the  contents  must  be 
moist  or  no  current  can  flow.  Blue  cup  bat- 
teries, Fig.  55,  contain  a  zinc  pole  in  dilute 
sulphuric  acid,  and  a  copper  pole  in  saturated  copper  sul- 
phate solution.  As  the  current  passes  from  zinc  through  the 


FIG.  54.— A 
dry  battery. 


ALUMINUM,   HEAVY  METALS,  ALLOYS          159 

solution  to  the  copper,  zinc  dissolves  from  the  zinc  plate,  and 
copper  deposits  on  the  copper  plate.  Other  metals  could  be 
used  in  place  of  zinc,  but 
the  latter  is  on  the  whole 
the  most  economical,  pro- 
ducing a  relatively  high 
electromotive  force. 

Brass  is  the  most  impor- 
tant alloy  of  zinc  which  is  in 
common  use,  but  the  latter 

metal   is    often   present   in    riG.55._A  blue  cup  battery  and  its  parts. 

other  alloys.     About  two 

hundred  and  fifty  thousand  tons  of  zinc  are  produced  in 
the  United  States  each  year,  and  the  rest  of  the  world 
produces  about  two  times  that  amount.  The  compounds  of 
zinc  are  analogous  to  those  of  magnesium.  It  is  to  be  kept 
in  mind,  however,  that  zinc  compounds  are  poisonous.  Zinc 
oxide,  ZnO,  is  used  in  paints,  being  called  zinc  white. 
Mixed  with  lard  or  vaseline,  it  forms  zinc  oxide  ointment. 
Zinc  chloride,  ZnCl2,  is  very  soluble  in  water.  It  is  used  for 
preserving  wood,  especially  railroad  ties.  The  salt  permeates 
the  wood  and  is  an  antiseptic ;  thus  it  is  death  to  the  germs 
that  are  the  cause  of  the  decay  of  wood.  White  vitriol  or 
zinc  sulphate,  ZnSO4 .  7  H^O,  is  another  very  common  zinc 
salt.  It  is  readily  soluble  in  water. 

Manganese  is  a  hard,  brittle  metal,  which  is  eight 
times  as  heavy  as  water,  and  melts  at  1300°.  In  na- 
ture it  is  found  mainly  as  pyrolusite,  which  is  manga- 
nese dioxide,  MnO2.  Alloys  of  manganese  and  iron  are 
used  injhe  steel  industry.  With  copper,  manganese  forms 
alloys  called  manganese  bronze.  These  are  very  hard  and 
strong.  Manganese  dioxide  is  often  used  in  preparing 
chlorine,  thus : 


160  CHEMISTRY  AND   DAILY  LIFE 

MnO2    +    4HC1    =    2H2O   -f  MnCl2   +   C12 

manganese       hydrochloric          water         manganous      chlorine 
dioxide  acid  chloride 

The  salts  of  manganese  are  quite  numerous.  The  manganous 
salts  are  pink  in  color,  and  the  chloride,  MnCl2,  sulphate, 
MnS04,  nitrate,  Mn(NO3)2,  and  acetate,  Mn(C2H3O2)2,  are 
soluble  in  water.  Manganese  acts  as  an  acidic  element  in 
manganates  and  permanganates.  Of  these  salts  potassium 
permanganate,  KMnO4,  is  of  practical  and  commercial  impor- 
tance. This  salt  crystallizes  in  needles  that  are  of  a  dark 
purple,  lustrous  hue.  The  salt  is  soluble  in  water  and  very 
often  serves  in  the  laboratory  as  an  oxidizing  agent.  It  is  also 
used  as  a  disinfectant. 

Nickel  is  malleable,  ductile,  and  8.9  times  as  heavy  as 
water.  Its  melting  point  is  about  1485°  C.  Nickel  coins 
consist  of  25  per  cent  nickel  and  75  per  cent  copper.  When 
alloyed  with  brass,  nickel  forms  German  silver.  Nickel  steel 
is  used  for  making  armor  plates  for  warships.  Nickel 
does  not  tarnish  readily  on  exposure  to  air,  and  hence 
it  is  often  used  to  plate  iron,  copper,  brass,  etc.  Nickel 
plating  is  carried  on  in  the  same  way  as  gold  or  silver  plat- 
ing. The  bath  for  nickel  plating  consists  of  a  solution  of 
nickel  ammonium  sulphate,  (NH4)2SO4 .  NiSO4 .  6  H2O,  and, 
of  course,  a  plate  of  solid  nickel  is  placed  in  the  solution  opposite 
to  the  object  to  be  plated.  The  electric  current  is  then  passed 
from  the  nickel  plate  through  the  solution  to  the  object  that 
is  to  receive  the  nickel  coating.  The  salts  of  nickel  are  green, 
and  when  soluble  they  yield  green  solutions. 

Cobalt  is  analogous  to  nickel  in  most  important  respects. 
Its  salts  when  dissolved  in  water  yield  dark  red  solutions,  and 
the  crystals  that  deposit  from  such  solutions  are  also  red,  for 
in  general  the  crystals  contain  water  of  crystallization. 
When  this  water  is  driven  off,  anhydrous,  i.e.  dry,  compounds 


ALUMINUM,   HEAVY    METALS,   ALLOYS          161 


are  formed  which  are  blue.     Cobalt  silicate  is  blue,  and  so  glass 

containing  cobalt  silicate  is  blue  glass,  also  called  smalt  glass. 

Indeed,  about  the  only 

practical  use  which  is  at 

present  made  of  cobalt  is 

in  the  production  of  blue 

glass,  blue  porcelain,  and 

blue    glazes    on    enamel 

ware.      Cobalt,    nickel, 

and  iron  are  metals  that 

are  attracted  by  a  magnet, 

and     are     consequently 

said  to  be  magnetic. 

Of  all  the  metals,  iron, 
ferrum,  is  the  most  use- 
ful. It  very  rarely  is 
found  in  the  free  state 
in  nature  except  in  me- 
teorites. The  most  im- 
portant ore  of  iron  is 
hematite,  which  is  an 
oxide  having  the  com- 
position Fe2O3.  It  is 
dark  red  in  color  and 
when  finely  ground  it 
serves  as  a  pigment  in 
paint,  being  called  red 

ocher.  The  rich  deposits  of  iron  ore  in  the  Lake  Superior  re- 
gion consist  of  hematite.  Magnetite,  or  magnetic  iron  ore, 
Fe3O4,  is  black.  Limonite,  2  Fe2O3 . 3  H2O,  is  a  hydrous 
oxide  of  iron.  It  is  yellow  in  color.  It  too  serves  as  a 
pigment  under  the  name  of  yellow  ocher.  These  oxides  and 
siderite,  ferrous  carbonate,  FeCO3,  form  the  chief  ores  of  iron. 


FIG.  56. 


A  blast  furnace  in  which  cast  iron 
is  made. 


162 


CHEMISTRY  AND   DAILY  LIFE 


To  obtain  metallic  iron  from  these  ores,  they  are  mixed  with 
charcoal,  coke,  or  coal  and  limestone  and  then  heated  in  a  blast 


FIG.  57.  — A  modern  blast  furnace,  showing  the  pig  iron  bed. 

furnace.  In  the  lower  part  of  the  furnace  carbon  dioxide  is 
formed,  for  here  air  is  blown  in  and  there  is  consequently 
sufficient  oxygen  to  form  carbon  dioxide.  The  latter  gas 
passes  upward  through  the  hot  carbon  and  is  converted  into 


ALUMINUM,   HEAVY  METALS,   ALLOYS         163 


carbon  monoxide,  thus : 

CO2  +  C  =  2  CO 

Then  the  carbon  monoxide  reduces  the  iron  ore  as  follows : 
Fe2O3  +  3  CO  =  2  Fe  +  3  CO2 

and  out  of  the  top  of  the  furnace  there  issues  carbon  dioxide, 
mixed,  however,  with  much  carbon  monoxide.  This  gas  is 
now  used  to  run  gas  engines  that  furnish  the  air  blast  for  the 
furnace.  The  molten  iron  accumulates  in  the  bottom  of  the 
furnace  and  is  tapped  off  from  time  to  time.  The  iron  is  run 
into  molds  of  sand  so  as  to  form  rough  bars,  or  pigs  as  they 
are  called.  The  cast  iron  thus  obtained  is  known  as  pig  iron. 
The  limestone  was  added  so  that  the  sand  and  silicates 
might  react  with  the  lime  to  form  a  fusible  calcium  silicate 
which  floats  on  top  of  the 
molten  iron  and  is  run 
off.  It  is  the  so-called 
slag.  It  is  now  used  for 
making  Portland  cement, 
whereas  formerly  it  was 
thrown  away. 

Cast  iron  always 
contains  considerable 
amounts  of  carbon  and 
other  impurities.  In 
fact  chemically  pure  iron 
is  not  obtainable  in  the 
market,  being  practically 
unknown.  The  different 

kinds  of  iron  and  steel,  then,  are  really  iron  containing 
various  other  substances.  The  carbon  content  especially 
determines  the  properties  of  the  iron.  Cast  iron  usually 
contains  from  2  to  3  per  cent  of  carbon  embedded  in  the  iron 


FIG.  58.  —  Cast  iron  as  it  appears  under  the 
microscope. 


164 


CHEMISTRY  AND   DAILY  LIFE 


as  graphite,  and  from  1  to  1.5  per  cent  of  carbon  as  iron 
carbide,  i.e.  chemically  combined  carbon.  From  0.5  to  4 
per  cent  of  silicon,  from  0.4  to  2  per  cent  of  phosphorus,  and 
sulphur  up  to  0.2  per  cent  are  also  generally  present.  Wrought 

iron  is  the  purest  iron  on 
the  market.  It  contains 
usually  less  than  1  per 
cent  of  foreign  ingredi- 
ents. The  carbon  con- 
tent is  generally  less  than 
0.2  per  cent.  Wrought 
iron  melts  at  1600°  C. 
and  can  be  welded  at 
from  900°  to  1100°.  In 
welding,  borax  or  sand  is 
used.  Thus  a  slag  of  iron 
borate  or  iron  silicate  is 
formed,  and  when  the 
iron,  brought  to  welding 

heat,  is  pounded  together,  this  slag  flies  off  and  the  clean  sur- 
faces of  the  pieces  of  iron  come  into  intimate  contact  so 
that  the  forces  of  cohesion  can  act  and  hold  them  together. 
Wrought  iron  is  made  from  cast  iron  by  puddling,  a  process 
which  consists  of  adding  iron  oxide  to  the  pig  iron  and  then 
heating  in  a  current  of  air  in  a  so-called  reverberatory  furnace. 
Thus  the  carbon  of  the  pig  iron  is  removed  because  it  unites 
with  the  oxygen  of  the  iron  oxide  and  of  the  air.  Other 
impurities  present,  like  silicon  and  phosphorus,  are  also 
oxidized  and  form  a  slag  with  some  of  the  iron.  Finally 
the  iron  is  almost  free  from  foreign  matter  except  a  few 
tenths  of  a  per  cent  of  carbon.  Malleable  iron  is  a  cheap  sub- 
stitute for  wrought  iron.  It  is  made  by  embedding  the  cast- 
ings in  iron  oxide  and  then  heating  for  about  two  days,  after 


FIG.  59.  — Wrought  iron  as  it  appears  under 
the  microscope. 


ALUMINUM,   HEAVY  METALS,   ALLOYS 


165 


which  all  is  cooled  off  slowly.  Thus  some  of  the  carbon  is 
removed  from  the  castings,  making  them  less  brittle  than  they 
were.  It  is  to  be  borne  in  mind  that  a  large  carbon  content 
makes  iron  brittle.  Sulphur  and  phosphorus  are  especially 
objectionable  in  iron,  for  they  make  it  quite  brittle.  Steel  is 
practically  free  from  sulphur  and  phosphorus.  Silicon  too  is 
present  only  in  small  amounts.  The  carbon  in  steel  varies 
from  about  0.2  to  1.6  per  cent,  mild  steel  containing  the 
smaller  amounts  of  car- 
bon. The  process  of 
hardening  and  temper- 
ing consists  of  heating 
the  steel  and  then  chill- 
ing it.  Very  sudden 
chilling  does  not  give 
the  carbon  a  chance  to 
crystallize  out  as  graph- 
ite, and  the  combined 
carbon  makes  the  steel 
wry  hard.  If  the  cool- 

irig     proceeds      Very      FlG.  60._ steel  as  it  appears  under  the  mi- 

slowly,    practically    all  croscope. 

the  carbon  crystallizes 

out,  and  a  soft  material  is  obtained.  By  suitable  chilling, 
the  proper  temper,  that  is,  the  desired  degree  of  hardness, 
may  be  obtained.  The  removal  of  the  carbon  from  cast 
iron  so  as  to  produce  steel  consists  essentially  in  oxidizing 
the  carbon.  This  is  accomplished  by  blowing  air  into 
the  molten  mass,  as  in  the  Bessemer  process,  in  which  a 
so-called  Bessemer  converter  is  used,  or  by  heating  cast 
iron  with  iron  oxide  on  the  hearth  of  a  furnace,  the  so- 
called  open  hearth  process.  When  the  cast  iron  contains 
much  phosphorus,  the  hearth  of  the  furnace  is  made  of  lime 


166 


CHEMISTRY  AND   DAILY   LIFE 


obtained  by  calcining  dolomite.  This  absorbs  the  phos- 
phorus, phosphates  of  calcium  and  magnesium  being  formed 
which  are  sold  as  fertilizer.  Nearly  thirty  million  tons  of 
iron  are  produced  yearly  in  the  United  States. 


FIG.  61. — An  open  hearth  furnace. 

Iron  forms  two  series  of  salts,  the  ferrous  and  the  ferric. 
Thus  there  are  ferrous  chloride,  FeCl2,  and  ferric  chloride, 
FeCl3,  ferrous  oxide,  FeO,  and  ferric  oxide,  Fe2O3,  etc.  In 
the  rusting  of  iron  hydrated  ferric  oxide  is  formed.  The  black 
oxide,  also  known  popularly  as  hammer  black,  which  results 
when  iron  is  heated  in  the  air,  is  ferrous  ferric  oxide, 
FeO .  Fe2O3  or  Fe3O4.  It  is  magnetic.  Iron  nearly  always 
acts  as  a  basic  element,  and  in  this  capacity  it  forms  salts 
with  practically  all  of  the  various  acids.  Only  a  few  of  the 
most  important  salts  of  iron  will  be  mentioned  here. 

Ferrous  sulphate,  also  known  as  green  vitriol  or  copperas, 
is  FeS04 .  7  H2O.  It  is  formed  by  the  oxidation  of  pyrite, 


ALUMINUM,   HEAVY   METALS,   ALLOYS         167 

FeS2,  which  occurs  in  nature  and  is  called  fool's  gold,  for  its 
crystals  are  of  a  lustrous,  golden  yellow  appearance.  Fer- 
rous sulphate  dissolves  readily  in  water.  It  is  used  in  making 
ink.  The  latter  contains  tannin  and  ferrous  sulphate.  The 
tannin  is  an  essential  ingredient  in  extract  of  nutgalls,  which 
is  added  to  the  ferrous  sulphate  solution.  Ferrous  sulphate 
is  also  used  as  a  disinfectant,  as  a  mordant  in  dyeing  fabrics, 
and  as  a  reducing  agent.  This  salt  is  cheap  and  readily 
obtainable  from  dealers  everywhere. 

Ferric  chloride,  FeCl3 .  6  H2O,  forms  a  dark  brown  crystal- 
line mass,  not  unlike  maple  sugar  in  appearance.  It  dissolves 
copiously  in  water,  also  in  alcohol  and  ether.  It  is  used  in 
medicine.  The  so-called  styptic  cotton  which  is  used  to  stop 
the  bleeding  of  wounds  consists  of  absorbent  cotton  treated 
with  a  solution  of  ferric  chloride.  This  material  not  only 
allays  bleeding  by  forming  a  clot  with  the  blood,  but  it  also 
acts  as  an  antiseptic,  thus  protecting  the  wound  from  germs. 

Blue  print  paper  consists  of  paper  that  has  been  coated  with 
a  solution  of  ferric  ammonium  citrate  plus  potassium  ferric 
cyanide.  The  latter  is  also  called  red  pmssiate  of  potash, 
K3Fe(CN)6.  This  paper  is  thus  coated  and  dried  in  the  dark. 
On  exposure  to  light,  the  ferric  citrate  is  in  part  reduced  to 
ferrous  citrate,  and  the  latter,  like  other  soluble  ferrous  salts, 
reacts  with  the  potassium  ferric  cyanide,  forming  a  blue  pre- 
cipitate, Fe3"  [Fe"'  (CN)  6]2,  Turnbull's  blue.  Where  the  paper 
has  been  protected,  no  precipitate  forms ;  and  so  when  after 
exposure  to  light  in  the  printing  process  the  paper  is  washed 
with  water,  the  parts  on  which  the  light  has  acted  appear 
blue,  whereas  the  parts  that  have  been  protected  appear 
white,  for  the  original  coating  on  the  blue  print  paper  is 
soluble  in  water.  It  is  to  be  remembered  that  if  blue  print 
paper,  not  exposed  to  light,  is  washed  with  water  in  the  dark, 
white  paper  is  obtained.  The  blue  printing  is  done  in  frames 


168  CHEMISTRY   AND   DAILY  LIFE 

similar  to  those  used  for  printing  photographs  from  negatives. 
The  latter  will  also  serve  for  making  blue  prints.  But  blue 
prints  are  commonly  made  by  using  tracing  cloth  or  paper 
that  is  not  too  thick  on  which  the  writing  or  drawing  that  is 
to  be  reproduced  in  blue  print  form  has  been  traced.  The 
thicker  the  paper,  the  longer  must  be  the  exposure  to  the 
light  to  get  the  desired  results.  Ammonia,  caustic  soda,  and 
caustic  potash  solutions  decompose  TurnbuU's  blue,  and  so 
may  be  used  to  write  white  characters  on  blue  prints.  The 
latter  are  stable  in  the  light,  also  toward  acids,  but  alkalies, 
as  just  mentioned,  destroy  the  blue  color. 

It  is  to  be  borne  in  mind  that  in  small  amounts  iron  is 
present  almost  everywhere.  In  all  soils  it  occurs.  To  the 
brown  sand,  earth,  and  the  brownish  and  yellowish  clays  it 
gives  their  characteristic  colors.  Our  sandstones  and  other 
rocks  all  contain  compounds  of  iron.  Indeed,  the  grains  of 
sand  in  the  sandstones  are  commonly  cemented  together  with 
oxides  of  iron.  Iron  compounds  are  present  in  the  tissues  of 
all  plants  and  animals.  The  green  leaf  contains  chlorophyl, 
for  the  formation  of  which  iron  is  essential,  and  the  blood  of 
animals  contains  haemoglobin,  in  which  iron  plays  an  important 
role.  In  fact,  without  iron  plants  and  animals  cannot  live. 
Nevertheless,  it  must  be  remembered  that  the  quantity  of 
iron  present  in  living  beings,  exceedingly  important  though  it 
is,  is  after  all  small ;  so,  for  instance,  the  human  body  contains 
only  about  0.004  per  cent  of  iron. 

QUESTIONS 

1.  Where  is  aluminum  found  in  nature,  and  in  what  form  ? 

2.  How  is  metallic  aluminum  made  ? 

3.  Mention  the  most  important  characteristics  of  metallic  alu- 
minum.   What  is  it  used  for  ? 

4.  What  is  thermite  ?     Describe  its  use. 


ALUMINUM,   HEAVY  METALS,   ALLOYS          169 

5.  What  is  alum,  and  what  is  it  used  for  ? 

6.  How  is  porcelain  made  ? 

7.  What  is  the   difference   between  porcelain   and    ordinary 
crockery  ware  ? 

8.  How  is  ultramarine  made  ?    What  are  its  uses  ? 

9.  How  much  alumina  can  be  made  from  45  grams  of  potassium 
alum? 

10.  What  are  the  noble  metals  ?     Describe  each. 

11.  For  what  purposes  is  gold  used ?     Why? 

12.  What  is  the  most  important  compound  of  silver  ?     What  are 
its  uses  ? 

13.  What  is  sterling  silver  ?     What  is  it  used  for  ? 

14.  Discuss  the  use  of  silver  compounds  in  photography. 

15.  What  is  a  negative  ? 

16.  Where  does  copper  occur  in  nature,  and  what  are  its  chief 
characteristics  and  uses  ? 

17.  Mention  three  important  alloys  of  copper. 

18.  Describe  the  most  common  compound  o"f  copper. 

19.  What  is  Bordeaux  mixture  ? 

20.  Of  what  use  is  mercury  ? 

21.  Mention  two  important  compounds  of  mercury  and  state 
what  they  are  used  for. 

22.  How  is  tin  obtained  from  its  ores  ? 

23.  What  is  pewter  ?    Britannia  metal  ?    Solder  ? 

24.  What  is  pink  salt  and  what  is  it  used  for  ? 
26.  What  is  mosaic  gold  ?    State  its  use. 

26.  Mention  the  properties  and  uses  of  lead. 

27.  What  does  a  lead  storage  battery  consist  of  ? 

28.  What   is   lead   arsenate?    Sugar   of   lead?    White    lead? 
What  is  each  used  for  ? 

29.  What  use  is  made  of  potassium  bichromate  ? 

30.  What  is  ammonium  molybdate  used  for  ? 

31.  How  does  zinc  occur  in  nature?    How  is  it  obtained  from 
these  ores  ? 


170  CHEMISTRY  AND   DAILY  LIFE 

32.  What  is  galvanized  iron  ? 

33.  Describe  an  ordinary  battery  such  as  is  used  for  ringing  a 
doorbell. 

34.  State  the  uses  of  zinc  oxide  and  zinc  chloride. 

35.  What  is  manganese  dioxide  used  for?    Write  the  equation 
expressing  the  chemical  changes. 

36.  Of  what  use  is  potassium  permanganate  ? 

37.  State  the  characteristics  and  uses  of  nickel. 

38.  How  proceed  to  nickel  plate  an  iron  spoon  ? 

39.  What  use  is  made  of  cobalt  ? 

40.  Name  the  chief  iron  ores  and  state  briefly  how  iron  is  obtained 
from  its  ores. 

41.  What  is  the  chief  difference  between  cast  iron  and  wrought 
iron? 

42.  How  is  steel  made,  and  how  is  it  tempered  ? 

43.  Why  are  sulphur  and  phosphorus  objectionable  in  iron? 

44.  What  is  malleable  iron  ?     How  is  it  made  ? 

45.  Explain  how  fertilizers  and  also  Portland  cement  are  made 
in  connection  with  the  production  of  iron  and  steel. 

46.  How  many  series  of  salts  does  iron  form  ?     Mention  two  com- 
pounds of  each  series. 

47.  What  is  ordinary  ink  ? 

48.  Describe  how  to  make  a  blue  print. 

49.  Discuss  the  occurrence  of  iron  in  plants  and  animals. 


CHAPTER  XII 
PAINTS,    OILS,   AND    VARNISHES 

THE  use  of  paints,  oils,  varnishes,  and  lacquers  dates  back 
to  ancient  times,  for  the  great  advantage  of  putting  a  pro- 
tective coating  upon  articles  of  wood,  metal,  etc.,  has  been 
appreciated  for  many  centuries.  That  such  coatings  fre- 
quently enhance  the  beauty  of  the  objects  to  which  they  are 
applied  was  also  duly  recognized. 

It  has  already  been  stated  that  oils  may  be  divided  into  two 
great  classes:  (1)  the  mineral  oils,  and  (2)  the  oils  of  organic, 
that  is  to  say,  of  plant  or  animal,  origin.  But  oils  may  also 
be  classified  according  to  their  use.  When  an  oil  is  to  be 
used  in  paint  it  must  be  .an  oil  that  will  dry  and  form  a  hard 
coating.  Oils  like  lard  oil,  olive  oil,  cottonseed  oil,  goose  oil, 
neat's-foot  oil,  and  the  various  mineral  oils  obtained  from 
petroleum  will  not  dry.  They  remain  smeary  when  they  are 
spread  upon  wood,  glass,  metal,  etc.,  and  they  are  conse- 
quently called  non-drying  oils.  On  the  other  hand,  linseed 
oil  and  poppy-seed  oil,  for  example,  will,  when  similarly  spread 
out  upon  objects,  gradually  dry  to  a  hard,  firm,  resistant 
coating.  Such  oils  are  termed  drying  oils.  While  mineral 
oils  are  obtained  from  the  distillation  of  crude  petroleum, 
animal  oils  are  obtained  by  heating  animal  fats  and  then 
subjecting  them  to  pressure,  and  vegetable  oils  are  prepared 
by  grinding  seeds  and  expressing  the  oil  from  them  either 
at  room  temperature  or  at  higher  temperatures.  Sometimes 
solvents  like  carbon  bisulphide  and  gasoline  are  used  in 
extracting  animal  or  vegetable  oils  from  fatty  animal  or  plant 

171 


172 


CHEMISTRY  AND   DAILY  LIFE 


matter.  Thus  the  fats  pass  into  the  solvent,  and  the  clear 
solution  containing  the  fat  may  be  filtered  from  the  solid 
residue  that  remains.  From  the  solution  the  oil  or  fat  is 

obtained  by  distilling  off  the  sol- 
vent, which  can  be  used  over  and 
over  again. 

Linseed  oil  is  the  most  impor- 
tant of  all  oils  for  use  in  paints. 
It  is  obtained  from  flaxseed, 
one  bushel  of  the  latter  yielding 
about  2.3  gallons  of  oil.  The  dry- 
ing qualities  of  linseed  oil  depend 
upon  the  fact  that  it  has  the  poiver 
to  absorb  oxygen  from  the  air. 
This  oxidized  linseed  oil,  also 
called  linoxin,  forms  a  tough, 
hard,  resistant  film  and  is  quite 
unlike  the  original  oil.  By  boil- 
ing linseed  oil  with  lead  oxide, 
oxides  of  manganese,  or  linoleates 
of  these  metals,  the  oil  dries  more 
rapidly,  and  the  substances  used  to  bring  about  this  effect  are 
called  driers.  They  are,  in  general,  oxidizing  agents  whose 
purpose  is  to  increase  the  rapidity  of  the  oxidation  of  linseed 
oil  to  linoxin.  Linseed  oil  itself  is  essentially  a  glycerine  salt 
of  linoleic  acid,  of  the  formula  (CigHaiO^  .  C3H5O3.  There 
are  also  present  in  the  oil,  to  the  extent  of  about  20  per  cent, 
olein,  palmitin,  etc.  American  linseed  oil  has  a  specific 
gravity  of  0.9336  at  15°  when  raw,  whereas  the  boiled  has  a 
specific  gravity  of  0.938.  It  boils  at  130°  C.  The  raw  oil 
obtained  by  pressing  ground  flaxseed  in  the  cold  is  very  light- 
colored,  whereas  oil  that  is  pressed  from  the  hot  seeds,  and 
also  boiled  oil,  is  dark  brown  in  color  and  has  a  greenish  tinge. 


FIG.  62. — A  press  used  in  re- 
moving oil  from  seeds. 


PAINTS,   OILS,   AND   VARNISHES  173 

Upwards  of  fifteen  million  bushels  of  flaxseed  are  raised 
annually  in  the  United  States,  which  would  represent  about 
thirty-four  million  gallons  of  linseed  oil.  Being  somewhat 
expensive,  linseed  oil  is  often  shamefully  adulterated  with 
cheaper  oils,  among  which  may  be  mentioned  fish  oil,  petro- 
leum oils,  rape,  cotton,  hemp,  and  corn  oil.  The  presence  of 
these  adulterants,  of  course,  lowers  the  quality  of  the  paint 
made  by  using  the  admixture.  Rosin  is  also  frequently  used 
to  adulterate  linseed  oil. 

When  linseed  oil  is  thoroughly  mixed  with  white  lead,  an  excel- 
lent paint  is  obtained.  This  is  usually  slightly  yellowish  in 
tint,  due  to  the  color  of  the  oil,  but  by  adding  a  very  small 
amount  of  blue  —  Prussian  blue,  for  example  —  this  yellow 
shade  is  dispelled  and  a  pure  white  paint  is  obtained,  which 


FIG.  63.  — A  barrel  of  white  lead. 

dries  rather  slowly,  but  is  exceedingly  durable,  especially  for 
outside  work  that  is  to  be  exposed  to  the  weather.  The 
paint  can  be  made  to  dry  more  rapidly  by  adding  small 
amounts  of  so-called  driers,  sometimes  also  termed  Japan 
driers.  As  stated  before,  they  consist  of  substances  that 
absorb  oxygen  from  the  air  and  then  give  it  off  to  the  oil,  at 


174  CHEMISTRY  AND   DAILY  LIFE 

least  in  part,  thus  hastening  the  oxidation,  that  is,  the  drying, 
of  the  oil.  Turpentine  is  a  substance  of  this  kind,  and  so  its 
addition  to  paint  hastens  the  process  of  drying.  Driers  are 
commonly  made  by  heating  lead  and  manganese  oxides 
(about  four  pounds  of  the  mixture)  with  a  gallon  of  linseed 
oil  to  about  500°  F.  and  stirring  till  a  uniform  mass  results. 
This  is  then  dissolved  in  turpentine  before  it  is  cold.  By 
adding  some  of  the  solution  thus  obtained  to  paint,  the  latter 
dries  rapidly.  Too  much  drier  must  not  be  used,  or  the  paint 
after  hardening  will  keep  on  oxidizing,  and,  thus  the  oil  will 
be  oxidized  too  much  and  spoiled,  or,  as  the  painters  say, 
"  burnt."  Any  drier  really  tends  to  make  the  paint  less 
durable.  There  is  much  linseed  oil  sold  as  boiled  oil  which  is 
not  boiled  at  all,  being  raw  oil  to  which  drier  has  been  added; 
it  is  popularly  called  "  bunghole  boiled  oil."  Often  zinc 
oxide  is  used  in  paints  together  with  white  lead,  even  to  the 
extent  of  half  and  half.  Paints  may  be  colored  by  adding  suit- 
able pigments.  These  should  be  finely  ground  and  then 
thoroughly  mixed  with  the  white  lead  and  oil.  Stirring 
is  really  not  as  good  as  grinding  all  together.  The  pigments 
remain  suspended  in  the  form  of  minute  particles  in  the  paint 
and  also  in  the  film  as  it  dries  after  it  has  been  applied.  As 
already  stated,  yellow  ocher  and  red  ocher  are  oxides  of 
iron.  They  are  cheap,  permanent,  and  excellent  pigments. 
Chrome  yellow  gives  a  beautiful  canary-yellow  shade,  but  it 
is  more  costly.  Vermilion  is  suphide  of  mercury,  cinnabar ; 
and  chrome  green,  which  is  very  brilliant  in  hue,  is  chromic 
oxide.  Prussian  blue  is  produced  by  adding  ferric  chloride 
to  a  solution  of  potassium  ferrocyanide,  K4Fe(CN)6.  It  is 
often  used  as  a  pigment.  Ultramarine  blue  too  is  used,  but 
it  is  not  as  permanent.  It  is  excellent  for  interior  work  in 
kalsomines,  etc.  Shades  of  gray  result  by  adding  small 
quantities  of  lampblack  to  white  paint.  //  is  always  best 


PAINTS,   OILS,   AND   VARNISHES 


175 


to  apply  two  or  more  thin  coats  of  paint  ivell  brushed  out,  rather 
than  to  attempt  to  cover  the  object  with  but  one  thick  coat. 
This  is  obvious,  for  a  thick  coat  will  not  dry  readily,  and  will 
tend  to  peel  off.  As  adulterants  of  white  lead,  chalk,  barytes, 
lead  sulphate,  kaolin,  and  a  mixture  of  zinc  sulphide  and 
barytes,  which  is  termed  lithophone,  are  frequently  used. 
None  of  these  should  be  present  in  high  grade  paint. 

Varnish  is  made  by  care/idly  melting  rosin  and  then  stirring 
in  linseed  oil  and  heating  the  mixture  together.     This  is  finally 


FIG.  64.  —  Gathering  turpentine. 

thinned  to  the  proper  consistency  with  turpentine.  Tur- 
pentine, CioHie,  is  obtained  by  distilling  the  sap  collected 
from  pine  trees.  After  the  turpentine  has  been  distilled  off, 


176  CHEMISTRY  AND   DAILY  LIFE 

the  rosin  remains  behind  in  the  retort.  Many  paints  contain 
varnish,  which  gives  a  gloss  to  the  film  that  forms  on  drying. 
Sometimes  benzine  or  gasoline  are  used  to  thin  varnishes  or 
paints  instead  of  turpentine,  but  this  is  bad  practice,  for  the 
film  that  remains  after  the  benzine  has  evaporated  is  not 
durable.  The  turpentine  never  wholly  evaporates ;  it  always 
leaves  a  film  of  its  own  which  together  with  the  varnish  or 
paint  film  makes  for  greater  durability.  If,  instead  of  rosin, 
copal,  a  fossil  rosin  found  in  Africa,  is  used  in  making  varnish, 
a  far  better  article  is  obtained,  but  it  is  also  much  more 
costly.  White  enamel  paints  are  superior  varnish  to  which 
white  lead  or  zinc  oxide  or  both  have  been  added  as  a  pig- 
ment. Other  colored  enamel  paints  result  by  introducing 
suitable  pigments. 

Shellac  varnish  consists  of  a  solution  of  shellac,  a  plant 
resin,  in  alcohol.  Either  wood  alcohol  or  grain  alcohol  may 
be  used.  White  shellac  is  bleached  shellac,  whereas  the 
brown  or  golden  shellac  has  the  natural  color  of  the  resin. 
Shellac  varnish  is  cheaper,  but  not  as  durable,  as  varnish 
made  from  oil  and  rosin. 


FIG.  65.  — Trinidad  asphalt  lake  near  the  edge. 


PAINTS,   OILS,   AND   VARNISHES 


177 


Black  varnishes  used  for  coating  iron  are  commonly  pre- 
pared by  dissolving  coal-tar  pitch  or  asphaltum  in  turpentine 
or  benzine  or  a  mixture  of  the  two.  Asphalt,  also  called 
asphaltum,  is  a  natural  pitch.  Large  quantities  of  it  are 
found  in  Trinidad.  It  is  also  used  for  making  excellent 
street  pavements,  by  mixing  it  with  sand,  dust,  and  finely 
crushed  stone  and  then  applying  this  on  a  foundation  of  con- 
crete, rolling  the  hot  mixture  securely  into  place  by  means  of 
heavy,  hot  steam  rollers. 


FIG.  66.  —  An  asphalt  street  in  New  York. 

Kalsomines  consist  of  a  thin  solution  of  glue  to  which 
slaked  lime  or  chalk  or  both  have  been  added.  These  mix- 
tures may  be  tinted  by  means  of  pigments  just  as  in  the  case 
of  paints.  Many  kalsomines  contain  plaster  of  Paris,  which 
forms  a  hard  coating  as  it  dries.  Kalsomines,  being  soluble 
in  water,  can  be  used  only  for  indoor  work,  preferably  on 
plastered  walls. 


178  CHEMISTRY  AND   DAILY  LIFE 

QUESTIONS 

1.  For  what  purposes  are  paints  and  varnishes  used? 

2.  How  may  oils  be  classified  ? 

3.  What  is  a  drying  oil  ?     Name  one  and  state  why  it  dries. 

4.  How  are  plant  oils  obtained  ?     Name  several  plant  oils. 

6.  How  are  animal  oils  prepared?     Name  several.     Are  these 
suitable  for  use  in  paint  ?     Why  ? 

6.  What  is  a  so-called  drier  ?     How  are  driers  used  ? 

7.  What  are  some  of  the  adulterants  used  in  linseed  oil  ? 

8.  Why  is  turpentine   better  than  benzine  in  paints  and  var- 
nishes ? 

9.  Describe  how  to  make  a  good  paint  for  outside  woodwork. 

10.  Mention  five  pigments  that  are  used  in  paints. 

11.  How  is  varnish  made  ? 

12.  What  is  shellac  varnish  ? 

13.  What  is  black  varnish  and  for  what  purpose  is  it  used  ? 

14.  What  is  asphalt  ?    For  what  is  it  used  ? 

15.  What  is  kalsomine  ? 


CHAPTER   XIII 
LEATHER,    SILK,    WOOL,    COTTON,   AND    RUBBER 

WEARING  apparel  is  made  of  materials  derived  from  animals 
or  plants.     Shoes  are  made  of  leather,  which  is  produced 


FIG.  67.  —  Silkworm,  cocoon,  egg-mass,  and  strands  of  silk. 
179 


180 


CHEMISTRY  AND   DAILY  LIFE 


from  the  skin  of  animals.  Furs,  too,  are  skins  of  animals  that 
have  been  subjected  to  certain  treatment.  Silk  is  made  from 
the  cocoon  of  the  silkworm.  The  silk  threads  are  spun  and 
then  woven  into  cloth.  Wool  is  the  hair  of  the  sheep.  It  is 
cleansed,  freed  from  fat,  spun,  and  then  woven.  Wool  and  silk 
are  substances  containing  carbon,  hydrogen,  oxygen,  sulphur,  and 


FIG.  68.  — A  sheep. 

nitrogen.  They  are  very  like  horn,  hoofs,  and  finger  nails  in 
chemical  composition,  and  when  burnt  all  of  these  give  a  pecul- 
iar odor,  namely,  the  odor  of  burnt  hair.  This  odor  is  due  to 
the  nitrogenous  decomposition  products  that  are  formed. 
Thus  it  is  quite  easy  to  distinguish  between  wool  and  silk 
on  the  one  hand,  and  cotton  on  the  other,  for  the  latter  does 
not  evolve  the  odor  of  burnt  hair  when  ignited.  Cotton, 
as  has  already  been  pointed  out,  is  practically  pure  cellulose 
(C6HioO6)OT  and  so  contains  no  nitrogen.  Moreover,  wool 


LEATHER,   SILK,   WOOL,   COTTON,   RUBBER     181 

and  silk  are  readily  soluble  in  caustic  alkalies,  whereas  cotton 
is  not.  Cotton,  too,  is  freed  from  mechanical  impurities, 
and  then  spun  and  woven.  Because  of  the  great  chemical 
differences  between  cotton  and  wool,  they  react  somewhat  differ- 
ently toward  dyestuffs ;  and  if  a  fabric  containing  both  cotton 
and  woolen  threads  is  dyed  in  the  same  liquid,  their  threads 
will  appear  of  different  shades.  Frequently  cloth  is  made 
by  using  cotton  warp  and  woolen  woof,  and  the  rather  rough 
bulky  nature  of  the  woolen  threads  after  the  process  of  milling 


FIG.  69.  — A  fleece  of  wool. 

hides  the  cotton  threads.  Such  cloth  is  often  quite  service- 
able, though  it  is  much  cheaper  than  cloth  that  is  all  wool, 
for  cotton  is  far  cheaper  than  wool.  Old  woolen  clothing  is 
frequently  taken  apart  and  used  over  again  to  make  new 
cloth.  In  this  process  the  threads  of  wool  are  necessarily 
much  shortened  and  the  cloth  woven  therefrom  is  much  less 
durable  than  new  goods.  By  using  some  cotton  in  the  warp 
of  such  made  over  woolens,  a  better  wearing  cloth  is  obtained. 
When  used  over  again  and  again,  however,  the  threads 
finally  become  so  short  as  to  be  worthless  except  as  a  fertilizer. 


182  CHEMISTRY  AND   DAILY   LIFE 

Moreover,  when  used  for  a  second  time,  there  is  cotton  mixed 
with  the  woolen  threads,  and  such  material  woven  on  cotton 
warp  is  commonly  known  as  shoddy.  Silk,  woolen,  cotton, 
and  linen  fabrics  are  now  dyed  almost  exclusively  by  means  of 


FIG.  70.  — An  old-fashioned  loom  of  colonial  days. 

the  aniline  dyestuffs,  also  called  coal-tar  colors.  As  a  rule  the 
colors  are  more  readily  fixed  upon  silk  and  woolen  fibers,  and 
less  readily  upon  the  cotton  and  linen  fibers.  Linen  is  made 
of  flax.  Like  cotton,  it  is  essentially  cellulose.  Mordants 
often  have  to  be  used  to  fix  dyestuffs  on  cotton  and  linen,  and 
sometimes  also  upon  wool  and  silk.  Dyestuffs  are  in  general 
either  slightly  acid  or  basic  in  character.  Mordants,  too,  are 


LEATHER,   SILK,   WOOL,   COTTON,   RUBBER     183 

either  weakly  acidic  or  basic  substances.  An  illustration 
will  serve  to  show  the  use  of  a  mordant.  Suppose  the  mor- 
dant is  tannic  acid ;  by  first  dipping  the  fabric  into  a  solu- 
tion of  this  acid,  the  fibers  take  up  a  certain  amount  of  the 
substance ;  and  when  they  are  now  immersed  in  a  dye  of 
basic  properties,  the  latter  is  fixed  upon  the  fiber. 

In  making  leather,  the  object  is  to  produce  a  material  that  is 
strong,  pliable,  insoluble  in  water,  and  not  subject  to  putrefac- 
tion. To  this  end  the  hides  or  skins  are  first  thoroughly 
softened  by  soaking  them  in  water.  They  are  then  immersed 
in  a  bath  of  slaked  lime  (milk  of  lime),  which  loosens  the  hair 
so  that  it  can  afterward  be  readily  removed  mechanically. 
The  process  of  removing  the  hair  is  called  depilation.  It  is 
also  sometimes  accomplished  by  simply  hanging  the  moist 
skins  up  so  that  slight  putrefaction  ensues,  whereupon  the 
hair  becomes  loose  and  can  readily  be  removed.  If  the  lime 
process  of  depilation  has  been  employed,  the  lime  in  the  skin 
must  be  removed  before  proceeding  farther.  This  is  done 
by  treating  in  a  bath  of  dilute  sulphuric  acid  and  then  washing 
with  water.  This  treatment  greatly  increases  the  bulk  of 
the  skin,  and  thus  it  is  in  excellent  condition  for  the  next  step. 
This  consists  of  immersion  in  extract  of  hemlock  or  oak  bark. 
This  extract  contains  tannin  which  unites  chemically  with  the 
fibers  of  the  hide  and  produces  the  compound  which  is  called 
leather.  Leather  does  not  dissolve  in  water  and  will  not 
putrefy.  It  requires  about  seventy  days  to  convert  the  hide 
into  leather  by  immersing  the  hide  in  extract  of  tanbark  as 
described.  Often  hides  are  put  into  vats  with  alternate 
layers  of  ground  tanbark,  and  water  is  then  added  to  cover 
all.  Thus  the  water  extracts  tannin  from  the  bark,  and 
leather  is  formed  by  the  union  of  the  hide  with  the  tannin. 
This  process  requires  a  much  longer  time.  Two  or  three 
months,  or  even  a  year,  may  be  required  to  secure  the  end  in 


184  CHEMISTRY  AND   DAILY  LIFE 

view.  Moreover,  the  bark  becomes  exhausted  and  the  hides 
have  to  be  placed  in  another  vat  with  new  bark  from  time 
to  time.  Nevertheless,  in  this  way  an  excellent  product  is 
obtained.  A  hide  gains  about  35  per  cent  in  weight  during 
the  process  of  tanning.  Other  barks  besides  oak  or  hemlock 
are  also  used.  So,  for  example,  sumach  is  employed  in  making 
morocco  leather  from  goatskins  or  imitation  morocco  from 


FIG.  71.  — A  scene  in  a  tannery.    Scrubbing  the  hides. 

sheepskins.  The  tanning  in  this  case  proceeds  rapidly; 
usually  it  lasts  only  a  day  or  two.  The  hair  of  the  goat- 
skins is  removed  by  the  lime  process,  but  the  excess  of  lime 
is  then  got  rid  of  by  using  hen  or  pigeon  manure.  This  keeps 
the  leather  soft.  In  other  cases  soft  leathers  are  secured  by 
removing  the  lime  by  means  of  sour  bran  prepared  by  treat- 


LEATHER,   SILK,   WOOL,   COTTON,   RUBBER     185 

ing  bran  with  water  and  sour  dough.  These  methods  of 
removing  the  lime  are  called  "  bating,"  for  by  employing 
infusions  of  the  materials  named  the  lime  is  removed  and  a 
large  swelling  of  the  hide  is  "  abated."  The  bate  liquor 
contains  organic  acids  which  form  soluble  salts  with  the  lime,  and 
these  then  can  be  washed  out.  Morocco  leather  is  dyed  with 
aniline  dyes.  Russia  leather  is  produced  in  a  similar  manner, 
only  the  tanning  is  done  with  willow  or  tamarack  bark.  Kid 
leather,  such  as  is  used  for  gloves,  is  made  of  goatskins  or 
sheepskins.  These  are  unhaired  with  lime,  and  then  treated 
with  sour  bran  to  remove  the  excess  of  the  lime.  The 
actual  tanning  consists  of  treating  the  skins  with  a  mixture 
of  common  salt,  alum,  flour,  and  egg  yolk  in  water.  This 
is  the  so-called  tawing  process.  The  alum  unites  with  the 
fibers  of  the  skin.  It  is  moreover  antiseptic  and  so  guards 
against  putrefaction.  The  result  obtained  is  a  white,  very 
soft,  pliable  leather. 

When  the  process  of  tanning  is  carried  so  far  that  the 
product  no  longer  yields  gelatine  on  being  boiled  in  water, 
we  have  sole  leather.  The  ordinary  soft  leathers  yield  some 
gelatine  on  boiling  in  water,  but  kid  leather  and  chamois 
skin  or  buckskin  do  not.  The  latter  are  made  from  skins  of 
deer,  goats,  or  sheep  in  much  the  same  way  as  morocco 
leather,  only  they  are  finally  treated  with  animal  oils  to  make 
them  very  soft  and  pliable.  The  excess  of  oil  is  removed 
by  means  of  alkalies.  Split  leather  is  made  by  splitting  thick 
hides,  such  as  cowhide,  by  means  of  machinery.  Three  or 
four  or  more  thin  layers  are  thus  made  from  one  skin.  These 
are  then  tanned  separately  and  the  grain  is  pressed  upon  them 
by  machines.  This  split  leather  is  cheap,  but  not  as  durable 
as  that  from  natural  thin  skins. 

Much  leather  is  tanned  in  America  by  the  chrome-tanning 
process.  The  hides  are  unhaired  and  cleaned  in  the  usual 


186  CHEMISTRY  AND  DAILY  LIFE 

manner.  They  are  then  soaked  in  a  dilute  solution  of  hy- 
drochloric acid  and  potassium  bichromate,  after  which  they 
are  placed  in  a  vat  containing  a  reducing  solution  like  sodium 
sulphite,  for  example.  Thus  hydrated  chromic  oxide  is  pre- 
cipitated, which  unites  with  the  fibers  of  the  hide,  much  the  same 
way  that  alumina  does  in  making  leather  for  kid  gloves.  The 
chrome  tanning  is  completed  in  the  course  of  a  few  hours. 
The  leather  is  finally  washed,  dyed,  and  oiled  as  leather 
made  with  tannin.  Box  calf  leather  is  chrome-tanned.  Its 
cut  edges  are  dark  green  in  color,  due  to  the  presence  of 
chromic  oxide. 

Skins  that  are  to  be  used  for  furs  are  tanned  by  the  alum 
process.  They  are  cleansed,  dried,  oiled,  treated  with  sour 
bran  and  water,  and  finally  tawed  with  a  solution  of  common 
salt  and  alum.  All  alum-tanned,  leather  when  thoroughly 
wet  gets  hard  when  it  dries,  for  water  dissolves  out  the  alum, 
and  the  leather  then  dries  hard  like  rawhide. 

Rubber  is  produced  from  the  milky  juice  or  so-called  latex 
of  the  india-rubber  trees,  which  grow  in  tropical  climes. 
The  best  rubber  comes  from  Brazil,  and  is  called  Para  rubber. 
The  milky  juice  is  obtained  from  the  trees  by  making  inci- 
sions in  the  bark  and  collecting  the  exuding  fluid  in  suitable 
vessels.  About  six  ounces  of  latex  are  collected  from  a  tree 
in  the  course  of  three  days,  and  this  yields  about  1.8  ounces 
of  rubber.  A  tree  yields  about  ten  pounds  of  rubber  per  year. 
The  world  produces  about  seventy-five  thousand  tons  of 
rubber  annually,  of  which  supply  about  one-half  comes  from 
Central  and  South  America,  the  tropics  of  Africa  and  Asia 
furnishing  the  other  half  in  approximately  equal  shares.  The 
island  of  Ceylon  alone  produces  about  3000  tons  per  year. 
While  the  bulk  of  the  rubber  is  still  obtained  from  trees  that 
grow  wild  in  tropical  forests,  a  fair  share  is  already  supplied 
by  cultivated  trees  of  rubber  plantations. 


LEATHER,   SILK,   WOOL,    COTTON,   RUBBER    187 


The  method  of  preparing  rubber  from  the  latex  is  still 
rather  primitive.  After  the  juice  has  been  collected,  it  is 
spread  upon  a  piece  of  wood,  about  four  feet  long,  shaped  like 
a  paddle.  Usually  the 
paddle  is  simply  dipped 
into  the  liquid.  It  is 
then  dried  by  holding 
the  paddle  over  a  fire  so 
that  the  smoke  comes 
into  contact  with  the 
drying  latex.  Frequently 
the  shells  of  oily  tropical 
nuts  are  used  as  fuel,  and 
the  creosote  and  oily  va- 
pors contained  in  the 
smoke  of  the  fire  perme- 
ate the  material  on  the 
paddle  and  help  to  pre- 
serve it.  When  the  first 
layer  is  dry,  the  paddle 
is  again  wet  with  the 
juice.  This  in  turn  is 
dried  on  over  the  fire, 
and  so  on,  till  many  lay- 
ers have  been  formed 
and  a  thick  covering  has 
been  obtained.  This  is 
then  slitted  and  stripped 
from  the  paddle.  It  is  called  caoutchouc,  and  is  placed  on 
the  market.  This  material  is  crude  rubber.  It  is  essentially 
a  hydrocarbon  corresponding  to  the  composition  (CsHs)*,  and 
is  probaby  a  condensation  product  of  the  hydrocarbon  iso- 
prene,  C5H8.  Turpentine,  Ci0Hi6,  is  a  related  substance. 


FIG.  72.  —  One  method  of  tapping  rubber 
trees. 


188  CHEMISTRY  AND   DAILY  LIFE 

Pure  Para  rubber  consists  of  about  94.6  per  cent  caoutchouc, 
0.14  per  cent  ash,  0.85  per  cent  water,  2.66  per  cent  resin,  and 
1.75  per  cent  protein  substances.  It  is  very  elastic  and  not 
readily  attacked  by  ordinary  chemical  agents.  It  does  very 
gradually  undergo  oxidation  on  exposure  to  the  air,  and  the 
oxygen  thus  taken  up  unites  with  the  caoutchouc  to  form  a 
hard,  brittle  compound.  Thus  it  is  that  all  rubber  gradually 
deteriorates,  whether  in  use  or  not.  The  rubber  goods  in 
the  market  are  practically  all  made  of  so-called  vulcanized 
rubber.  The  process  of  vulcanizing  rubber  was  discovered 
by  Goodyear  in  1843.  It  consists  essentially  of  adding  about 
10  per  cent  of  sulphur  to  the  caoutchouc,  then  molding  the 
desired  article  from  this  mixture,  and  heating  out  of  contact 
with  the  air  to  140°  to  150°  C.  A  portion  of  the  sulphur 
unites  chemically  with  the  caoutchouc ;  the  remainder,  how- 
ever, is  nevertheless  required  to  produce  the  desired  product. 
Such  vulcanized  rubber  is  more  elastic,  less  porous,  and  not  at 
all  sticky  as  compared  with  caoutchouc.  It  is  also  less  soluble 
in  solvents  like  carbon  bisulphide,  turpentine,  benzine,  and 
naphtha,  which  are  the  common  solvents  for  caoutchouc. 
Furthermore,  vulcanized  rubber  does  not  lose  its  elasticity 
when  subjected  to  cold.  Sometimes  rubber  is  vulcanized 
without  heating,  by  simply  treating  it  with  chloride  of  sul- 
phur, which  is  a  liquid  at  room  temperatures.  This  is,  how- 
ever, not  as  satisfactory  for  many  purposes.  White  rubber 
articles  are  made  by  incorporating  chalk  or  kaolin  mechani- 
cally with  the  rubber.  Red  rubber  is  similarly  colored  by 
using  antimony  sulphide,  black  rubber  by  means  of  lamp- 
black, blue  rubber  by  using  ultramarine  blue,  and  so  on. 
Rubber  coats,  boots,  shoes,  etc.,  are  made  by  spreading 
upon  the  cloth  fabrics  a  plastic  layer  of  caoutchouc  properly 
mixed  with  sulphur.  The  vulcanizing  is  then  accomplished 
by  heating  to  140°  to  150°  C.  Treating  with  a  solution  of 


LEATHER,   SILK,   WOOL,   COTTON,   RUBBER     189 

chloride  of  sulphur  in  carbon  disulphide  is  also  in  vogue,  but 
it  does  not  yield  as  good  results. 

Hard  rubber,  also  called  vulcanite  or  ebonite,  is  obtained 
when  caoutchouc  is  mixed  with  about  thirty  to  fifty  per  cent 
of  sulphur  and  then  heated  to  temperatures  that  are  from 
thirty  to  forty  degrees  higher  than  tliose  employed  in  mak- 
ing soft  vulcanized  rubber.  Hard  rubber  is  used  in  making 
combs,  buttons,  knife  handles,  bowls,  trays,  and  many  other 
useful  articles. 

Rubber  is  a  non-conductor  of  electricity  and  hence  is  much 
used  as  an  insulating  material  for  electrical  wires.  Hard  rub- 
ber, too,  is  used  as  an  insulator  on  electrical  machinery  and 
appliances.  Gutta-percha,  which  comes  from  the  gum  of  the 
percha  tree,  is  chemically  very  similar  to  rubber.  It  is,  how- 
ever, not  as  elastic.  Being  a  good  insulator,  it  is  much  used 
for  covering  wires  and  cables.  It  also  serves  like  hard  rubber 
for  the  manufacture  of  various  articles. 

The  demand  for  rubber  has  increased  enormously  of  recent 
years  on  account  of  the  use  of  rubber  tires  on  automobiles 
and  other  vehicles.  Attempts  have  consequently  been  made 
to  make  rubber  artificially.  While  these  have  been  success- 
ful, the  synthetic  rubber  thus  produced  is  nevertheless  still 
so  costly  that  it  is  not  yet  made  on  a  commercial  scale. 
Rubber  substitutes  are,  however,  on  the  market.  These 
consist  essentially  of  products  obtained  by  heating  certain 
oils,  notably  corn  oil,  to  higher  temperatures,  where  partial 
decomposition  ensues  and  a  somewhat  elastic  mass  is  ob- 
tained, which  is  worked  up  with  sulphur.  Such  rubber  sub- 
stitutes are  not  at  all  the  equal  of  real  rubber,  and  they  are 
in  general  only  employed  when  mixed  with  some  of  the  gen- 
uine article. 


190  CHEMISTRY  AND   DAILY  LIFE 

QUESTIONS 

1.  What  are  the  different  sources  from  which  the  material  for 
making  wearing  apparel  is  obtained  ? 

2.  How  distinguish  between  wool  and  cotton  ? 

3.  What  is  shoddy  ? 

4.  What  is  linen? 

5.  How  are  fabrics  dyed  ? 

6.  What  is  a  mordant  ?     Describe  its  use. 

7.  Describe  the  process  of  making  leather  by  use  of  oak  tanbark  ? 

8.  What  is  sole  leather  ? 

9.  What  is  split  leather  ? 

10.  How  is  leather  for  white  kid  gloves  made  ? 

11.  How  is  " buckskin"  leather  made? 

12.  How  are  skins  that  are  to  be  used  for  furs  treated  ? 

13.  Describe  the  process  of  chrome  tanning. 

14.  How  is  rubber  prepared  from  the  rubber  trees  ? 

15.  What  is  meant  by  vulcanizing  rubber  ?    How  does  this  process 
improve  the  material  ? 

16.  How  is  hard  rubber  obtained  ?    What  is  it  used  for  ? 

17.  What  is  gutta-percha,  and  what  are  its  uses  ? 


CHAPTER  XIV 
THE  SOIL 

LARGE  areas  of  the  earth's  surface  are  covered  with  a  loose 
layer  of  sand  and  clay  mixed  with  the  remains  of  plants  that 
have  decayed.  This  layer  is  called  soil.  Its  depth  varies 
greatly,  being  usually  only  from  six  to  twelve  inches,  though 
soils  may  at  times  be  several  feet  deep,  as  the  experience  that 
has  been  gathered  incidentally  in  digging  wells  has  shown. 
Living  organisms  of  various  kinds  and  variable  amounts  of 
water  and  air  are  also  present  in  soils.  The  soil,  which  is  the 
surface  layer,  rests  upon  the  subsoil,  which  differs  from  the 
upper  layer  in  that  it  contains  less  organic  matter  and  is 
generally  lighter  in  color.  The  subsoil  gradually  grades  off 
into  the  solid  rock  below,  as  is  illustrated  by  Fig.  73. 


FIG.  73.  —  Soil  formation  showing  the  transition  of  rock  to  soil. 
191 


192  CHEMISTRY  AND   DAILY  LIFE 

Sand  and  clay,  which  form  by  far  the  larger  portion  of 
soils,  are  mineral  matter  consisting  of  particles  of  silica,  sili- 
cates, and  frequently  also  carbonates,  that  have  been  broken 
off  from  large  masses  of  solid  rock.  This  breaking  down  or 
disintegration  of  solid  rock  into  small  fragments  is  very  im- 
portant in  the  process  of  soil  formation.  It  proceeds  to- 
day just  as  it  has  been  going  on  in  the  past.  The  chief  agen- 
cies which  are  active  in  the  process  of  making  soil  are  water, 
wind,  animals,  and  plants.  The  effect  of  each  of  these  will 
now  be  considered. 

The  work  of  water  and  the  air  in  disintegrating  rocks  is  com- 
monly  termed  weathering  of  rock.  It  proceeds  constantly. 
The  action  of  water  and  air  is  in  part  purely  physical,  that 
is,  mechanical,  and  again  it  is  partly  chemical  in  its  nature. 
All  rocks  are  more  or  less  porous  and  consequently  allow  water 
to  soak  into  them.  As  this  freezes,  it  expands  and  bursts 
the  rocks,  which  then  gradually  crumble.  Again,  the  water 
dissolves  and  carries  away  some  of  the  material  of  which 
rocks  are  composed.  This  effect  is  chemical  in  character, 
and  it  further  weakens  the  structure  of  the  rock  and  also 
reduces  the  size  of  the  particles. 

The  waters  of  shallow  streams  roll  the  gravel  stones  along 
their  beds.  As  these  pebbles  are  carried  along,  they  strike 
against  one  another ;  their  corners  are  knocked  off ;  they  are 
ground  smooth  by  the  continual  rubbing;  and  at  the  same 
time  they  are  also  reduced  in  size  by  the  solvent  action  of  the 
water.  Thus  the  particles  become  smaller  and  smaller  till 
they  are  nothing  but  sand.  These  finer  particles  then  are 
generally  the  less  soluble  portions  of  the  disintegrated  rocks, 
and  as  they  are  carried  forward  by  the  stream  they  finally 
arrive  in  still  water,  where  they  sink  to  the  bottom.  When 
the  stream  eventually  changes  its  course,  they  appear  as 
real  sand.  In  a  similar  way  the  waves  on  the  shores  of 


THE  SOIL  193 

lakes    and    seas    are    continually   reducing   rocks    to    fine 
particles. 

In  the  form  of  ice,  water  is  a  very  important  mechanical  agent 
in  the  disintegration  of  rocks.  So  the  cakes  of  floating  ice  as 
they  are  carried  down  by  rapid  streams  in  spring  are  com- 
monly covered  with  mud,  rocks,  and  not  infrequently  por- 
tions of  trees  and  other  detritus  that  has  been  torn  away  from 
the  banks.  The  ice  on  the  shores  of  lakes  incloses  bowlders 
and  shoves  them  upon  the  beach  during  the  spring.  Geologists 
have  gathered  evidence  which  shows  that  centuries  ago  the 
North  American  continent,  about  as  far  south  as  the  Ohio 
River,  was  covered  with  ice  to  a  great  depth ;  see  map,  Fig. 
74.  These  immense  glaciers  moved  southward  like  great 
rivers,  only  extremely  slowly.  Their  movement  was  doubt- 
less entirely  similar  to  that  of  the  glaciers  that  exist  at  the 
present  time  in  Switzerland,  Greenland,  and  in  the  Rocky 
Mountains.  This  large  field  of  glacial  ice  carried  everything 
before  it.  It  gathered  up  great  rocks,  which  froze  into  the 
ice,  and  thus  this  heavy  rock-shod  surface  slowly  moved  over 
the  underlying  rocks,  crushing  and  grinding  them  to  fine 
powder,  which  is  now  the  sand  and  clay  of  the  regions  that 
have  thus  been  visited  by  the  glaciers.  The  latter  have 
thus  been  invaluable  in  preparing  the  land  for  agricultural 
purposes.  All  over  the  North  where  the  glaciers  have  passed 
may  be  found  huge  bowlders  that  escaped  crushing  and  were 
left  behind  when  the  ice  melted.  These  are  of  very  hard 
material  and  so  are  commonly  called  "  hard  heads."  They 
are  round  and  smooth  because  of  the  grinding  and  rolling 
action  to  which  they  were  subjected.  It  is  clear,  then,  that 
the  soils  of  these  glaciated  regions  have  really  been  transported 
to  their  present  localities  by  the  glaciers.  In  the  South,  on  the 
other  hand,  where  the  glaciers  have  not  been,  the  soils  have  not 
been  transported.  Here  they  have  been  formed  from  the 


194 


CHEMISTRY  AND   DAILY  LIFE 


underlying  rock  upon  which  they  rest  to-day.  Such  soils 
that  have  been  formed  by  the  weathering  of  the  particular 
rock  upon  which  they  rest  are  called  sedentary  soils,  whereas 


FIG.  74.  —  Map  of  North  America,  showing  the  southern  limit  of  the  glaciers. 

soils  that  have  been  carried  from  other  localities  to  the  place 
where  they  are  found  are  termed  transported  soils.  Thus 
the  soils  made  by  glaciers  belong  to  the  latter  class.  But 
transported  soils  are  also  found  in  regions  that  have  not  been 
glaciated,  for  wind  and  water  are  active  everywhere  in 
transporting  soil  material.  Thus  the  rich  soil  in  the  lower 


THE   SOIL  195 

regions  of  river  valleys  consists  largely  of  material  which  has 
been  brought  down  by  the  river  from  the  higher  portions  of 
the  valley;  and  since  this  material  has  in  many  cases  been 
brought  from  various  rock  formations,  the  resulting  soil  gen- 
erally possesses  a  greater  fertility  than  if  it  had  been  formed 
by  the  weathering  of  any  one  kind  of  rock.  The  rich  bottom 
lands  of  many  of  our  rivers  are  excellent  examples  of  this. 
A  good  overflow  from  a  river  is  often  as  beneficial  as  a  covering 
of  manure.  It  should,  however,  be  remembered  that  soil 
once  formed  is  liable  to  be  washed  away.  Soils  composed  of 
very  fine  material  are  thus  carried  off  most  readily,  because 
the  rain  water  does  not  soak  into  them  rapidly,  but  accu- 
mulates on  the  surface  and  runs  off  in  little  streams  which 
carry  the  fine  topsoil  with  them.  This  is  a  decided  loss  for 
the  farmer,  for  it  is  the  best  part  of  the  soil  that  is  thus  washed 
away. 

In  the  formation  of  soils,  the  work  of  the  wind  consists 
largely  in  carrying  and  distributing  particles  of  the  soil ;  but 
it  nevertheless  also  takes  part  in  the  process  of  actually  dis- 
integrating rocks  and  grinding  coarser  grains  to  finer  ones. 
So  when  particles  of  sand  are  blown  against  solid  rock,  the 
latter  is  gradually  worn  away  and  becomes  soil.  The  action 
of  the  wind  in  blowing  particles  of  sand  against  rock  surfaces 
is  comparable  with  the  effect  produced  by  the  water  of  a 
stream  as  it  causes  sand  and  pebbles  to  grind  on  the  bottom 
of  its  bed.  Sand  dunes,  like  those  along  the  shores  of  Lake 
Michigan,  for  example,  are  good  illustrations  of  wind-borne 
materials.  While  these  particular  dunes  are  worthless  for 
farming,  there  are  nevertheless  large  areas  of  wind-formed 
soils,  as,  for  example,  the  loess  just  west  of  the  Mississippi 
River,  which  are  quite  fertile  and  deep.  The  air  also  acts 
chemically  in  the  process  of  soil  formation.  Many  rocks  and 
rock  particles  that  contain  ferrous  silicates  are  oxidized  to 


196 


CHEMISTRY  AND   DAILY  LIFE 


ferric  compounds  by  the  oxygen  of  the  air,  and  thus  farther 
disintegration  results.  This  action  is  especially  facilitated 
by  water,  which  always  contains  oxygen  in  solution.  Carbon 
dioxide,  too,  is  always  present  in  water  that  has  been  in  contact 


FIG.  75. —  Sand  dunes  on  the  shore  of  Lake  Michigan. 

with  the  air,  and  this  dissolves  many  rocks,  especially  those  that 
consist  of  the  carbonates  of  calcium,  magnesium,  iron,  etc. 

Animals  are  also  important  agents  in  soil  formation.  So> 
for  example,  rabbits,  moles,  prairie  dogs,  and  other  burrowing 
animals  dig  into  the  earth  and  throw  out  raw  subsoil  and 
pieces  of  rock,  all  of  which  help  to  make  new  soil  through 
the  further  action  of  alternate  freezing  and  thawing.  Even 
the  action  of  those  humble  creatures,  the  earthworms,  is 
of  material  consequence  in  the  work  of  forming  soils.  They 
bring  a  portion  of  the  subsoil  to  the  surface,  draw  dead 
leaves  and  other  vegetable  material  into  their  burrows,  and 
pass  large  quantities  of  the  soil  through  their  bodies,  de- 
positing it  on  the  surface  at  a  rate  estimated  as  ten  tons  per 


THE  SOIL  197 

acre  annually.  Ants  are  also  active  soil  formers,  and  in  some 
warm  climates,  as  in  Africa,  they  perform  much  the  same 
work  as  the  earthworm. 

Growing  plants  send  their  roots  into  rocks  and  soils,  thus 
loosening  them  up  and  rendering  them  porous,  a  condition 
that  allows  air  and  water  to  enter  more  readily.  Roots 
sometimes  penetrate  the  soil  to  great  depth,  and  as  they  de- 
cay after  the  death  of  the  plant,  they  leave  in  the  soil  little 
channels  through  which  water  gains  access  to  the  lower  strata. 
This  water  always  contains  carbon  dioxide  from  the  air ;  and 
as  already  stated,  it  dissolves  portions  of  the  soil  and  thus 
makes  them  available  as  food  for  the  rootlets  of  new  plants. 
The  roots  and  root  hairs  of  living  plants  also  give  off  carbon 
dioxide,  which  is  absorbed  by  the  soil  water  and  then  exer- 
cises similar  solvent  action  upon  the  soil.  Indeed,  this  car- 
bonated water  in  the  soil  is  probably  the  chief  agent  that  dissolves 
rocks  and  soil  materials,  thus  enabling  plants  to  obtain  the 
necessary  elements  for  their  growth.  It  must  not  be  for- 
gotten that  all  of  these  effects  of  plants  in  rock  disintegra- 
tion and  soil  formation  are  slight  in  any  one  year;  they  never- 
theless amount  to  a  great  deal  when  carried  on  through  hundreds 
of  years.  A  small  crack  in  a  rock  enables  the  tiny  plants  to 
work  their  way  into  it.  As  they  grow,  they  exert  great  pres- 
sure, which  is  frequently  sufficient  to  split  the  rock  asunder. 
It  is  not  uncommon  to  see  bowlders  weighing  several  tons 
split  in  two  and  a  tree  growing  up  between  the  pieces. 

Peat  bogs  are  formed  in  swampy  places  or  shallow  ponds 
where  plants  grow  year  after  year,  dying  at  the  end  of  the 
season,  and  falling  to  the  ground  or  into  the  water.  As  this 
process  is  repeated  for  many  years,  there  finally  results  a 
large  accumulation  of  vegetable  material.  This  rots  more 
or  less  and  so  comes  to  be  a  type  of  soil.  If  the  rotting  takes 
place  under  water,  it  proceeds  very  slowly  and  results  in  the 


198  CHEMISTRY  AND  DAILY  LIFE 

formation  of  peat,  which  is  fairly  solid  and  generally  shows 
some  of  the  original  shapes  of  the  plants.  As  stated  in  Chap- 
ter IX,  this  material  is  in  the  first  stage  toward  the  formation 
of  coal.  In  the  low  and  undrained  marshes  of  this  country 
there  are  countless  tons  of  peat  waiting  to  be  used  for  fuel 
or  other  purposes.  Peat  has  been  an  important  fuel  in  Europe 
for  hundreds  of  years.  If  the  decaying  vegetable  matter  is 
exposed  to  the  air  and  becomes  alternately  water-soaked  and 
dry,  it  decomposes  rather  rapidly  and  forms  muck.  This 
is  soft  and  spongy  and  does  not  show  any  trace  of  what  it 
formerly  was.  It  is  usually  mixed  with  sand  and  clay  which 
have  been  washed  over  it. 

When  a  small  quantity  of  soil  is  viewed  with  the  naked 
eye,  it  appears  made  up  of  small  particles  which  look  like 
little  grains.  They  are  tiny  pieces  of  disintegrated  and  de- 
cayed rock  which  range  in  size  from  those  that  may  be  read- 
ily seen  to  those  that  are  as  fine  as  dust.  Besides  these  rock 
particles,  which  are  the  mineral  matter,  there  are  also  present 
pieces  of  roots,  stems,  leaves,  etc.,  which  are  the  organic  mat- 
ter. In  peat  soil  the  organic  matter  predominates.  The  rock 
particles  that  are  large  enough  to  be  readily  seen  are  called 
sand,  while  the  very  fine  dustlike  particles  are  termed  silt 
and  clay.  The  latter  represents  the  very  finest  material. 
A  magnifying  glass  is  required  to  see  the  finest  sand  particles 
and  to  distinguish  the  silt  from  the  clay.  There  are  several 
important  classes  of  soils  that  are  commonly  recognized. 
So  when  the  sand  particles  are  abundant,  the  soil  is  called  a 
sandy  soil.  If  the  sand  grains  are  not  abundant,  and  the 
soil  is  quite  floury  when  crushed,  it  is  a  clay  soil.  When  there 
is  a  considerable  proportion  of  sand  present  but  also  some 
clay,  the  soil  is  called  a  loam.  The  popular  expressions  sandy, 
light  sandy,  loam,  heavy  clay  loam,  and  clay,  all  express  the 
relative  proportions  of  clay,  silt,  and  sand  in  the  soil.  Loams 


THE  SOIL  199 

generally  make  good  soils.  They  are  usually  fertile  and  easily 
worked.  The  vegetable  matter  in  sands,  loams,  and  clays  is 
called  humus,  and  muck  soils  are  sometimes  spoken  of  as 
humus  soils.  Real  humus  is  vegetable  matter  so  completely 
decayed  that  one  cannot  tell  what  it  was  originally. 

Though  thus  made  up  of  minute  rock  particles  and  tiny 
pieces  of  decayed  roots  and  stems,  the  soil  nevertheless  con- 
tains the  substances  necessary  to  make  plants  grow  and  develop 
to  maturity.  When  a  seed  is  placed  in  soil  of  proper  moisture 
content,  it  absorbs  water  and  germinates.  Firming  the  soil 
about  the  seed  brings  it  into  closer  contact  with  the  moisture 
and  hastens  the  absorption  of  water.  But  besides  moisture, 
germinating  seeds  require  oxygen,  and  so  while  the  soil  must 
be  in  close  contact  with  the  seed  and  contain  sufficient 
moisture,  it  must  not  be  water-logged  nor  so  closely  packed 
around  the  seed  as  to  exclude  air,  otherwise  the  seed  will  fail 
to  germinate  and  will  actually  rot. 

After  germination  has  taken  place  a  seed  will  continue  to 
grow  for  some  time  at  the  expense  of  the  reserve  food  which 
it  contains ;  but  sooner  or  later  growth  will  cease  unless  cer- 
tain chemical  elements  are  available  for  absorption  by  the 
plant.  These  so-called  essential  elements  without  which  the 
plant  cannot  grow  are  nitrogen,  phosphorus,  sulphur,  potas- 
sium, calcium,  magnesium,  iron,  and  hydrogen  and  oxygen 
in  the  form  of  water.  Plants  indeed  also  contain  other  ele- 
ments like  sodium,  chlorine,  and  silicon,  but  these  are  gen- 
erally considered  as  non-essential,  for  plants  have  been  grown 
without  them.  It  should  be  clearly  understood  that  the 
chemical  elements  mentioned  are  absorbed  by  the  rootlets  of  the 
plants  in  the  form  of  salts  that  are  in  solution  in  the  soil  water. 
Humus  soils  contain  a  great  deal  of  carbon,  but  the  plant 
gets  its  carbon  content  from  the  carbon  dioxide  of  the  air  through 
its  leaves  (see  Chapter  IX),  and  not  from  the  soil  through  its 


200  CHEMISTRY  AND  DAILY  LIFE 

roots.  Some  of  the  elements  are  used  to  build  up  the  organic 
structure  of  the  plant,  while  others  remain  in  the  plant  as 
salts.  So  while  hydrogen  and  oxygen  unite  to  form  water, 
hydrogen,  oxygen,  and  carbon  combine  to  form  starch,  cel- 
lulose, sugar,  fats,  and  oils  (see  Chapter  IX).  Nitrogen, 
sulphur,  and  phosphorus  together  with  carbon,  hydrogen,  and 
oxygen  form  the  very  complex  substances  called  proteins  (see 
Chapter  IX),  which  are  absolutely  necessary  for  the  growth 
of  the  plant. 

Each  crop  taken  from  the  soil  removes  a  certain  amount  of 
the  essential  elements  which  the  soil  contains.  The  amounts 
of  such  elements  thus  removed  have  been  carefully  ascer- 
tained by  chemical  analyses.  These  results,  together  with  the 
chemical  analyses  of  the  soils  themselves,  have  shown  that 
most  soils  contain  enough  of  the  essential  elements  to  furnish 
crops  for  hundreds  of  years.  Nevertheless,  as  will  be  further 
explained  below,  the  available  supply  of  these  elements  is  so 
limited  that  additional  amounts  must  be  added  either  as  com- 
mercial fertilizers  or  as  farm  manures,  if  crop  production  is 
to  continue  at  a  profit.  Chemical  analyses  have  also  shown 
that  an  acre  surface  foot  of  soil  may  contain  enough  potas- 
sium to  last  1500  years,  and  supplies  of  phosphorus  sufficient 
for  200  to  500  years,  of  nitrogen  for  100  to  300  years,  and 
sulphur  for  200  to  300  years.  The  amounts  of  plant  food 
removed  from  an  acre  by  some  of  our  common  crops  are 
given  in  Table  8. 

Besides  the  essential  elements  above  mentioned,  plants 
require  large  quantities  of  water  throughout  their  period  of 
growth.  This  water  is  necessary  to  dissolve  the  soluble  salts 
in  the  soil  and  to  convey  them  through  the  walls  of  the 
rootlets  into  the  plant.  Water  is  also  needed  to  keep  the 
cell  walls  of  the  leaf  moist  so  that  it  may  absorb  carbon 
dioxide,  and  regulate  the  temperature  of  the  plant ;  for  plants 


THE  SOIL 


201 


JEAN  BAPTISTS  BOUSSINGAULT,  1802-1887. 

The  first  chemist  who  analyzed  crops  and  manure  and  studied  closely  the 
relations  of  chemistry  to  farming. 


202 


CHEMISTRY  AND  DAILY  LIFE 


TABLE  8 

AMOUNT  OF  PLANT  FOOD  REMOVED  FROM  THE  LAND  BY  VARIOUS 
CROPS,  EXPRESSED  IN  POUNDS  PER  ACRE 


KIND  OF  CROP 

DRY  WEIGHT 
OF  CROP 

N 

p 

s 

K 

Ca 

Mg 

Ib. 

Ib. 

Ib. 

Ib. 

Ib. 

Ib. 

Ib. 

Wheat  (grain),  30bu. 

1530 

34 

6.2 

2.5 

7.7 

0.7 

2.1 

Wheat  (straw)  .     . 

2653 

16 

3.0 

3.7 

16.2 

5.8 

2.1 

Total  crop     .     . 

4183 

50 

9.2 

6.2 

23.9 

6.5 

4.2 

Barley  (grain),  40bu. 

1747 

35 

7.0 

2.6 

8.0 

0.8 

2.4 

Barley  (straw)  .     . 

2080 

14 

2.0 

3.0 

21.5 

5.6 

1.7 

Total  crop     .     . 

3827 

49 

9.0 

5.6 

29.5 

6.4 

4.1 

Corn  (grain),  30  bu. 

1500 

28 

4.3 

2.5 

5.4 

0.3 

2.0 

Corn  (stalks)     .     . 

1877 

15 

3.5 

2.2 

24.7 

7.5 

3.3 

Total  crop     .     . 

3377 

43 

7.8 

4.7 

30.1 

7.8 

5.3 

Red  clover  hay  .     . 

3762 

98 

10.8 

6.1 

69.2 

63.9 

16.9 

Alfalfa  hay   .     .     . 

9000 

197 

17.4 

25.9 

176.7 

151.1 

31.8 

Turnips  (roots) 

3126 

61 

9.7 

23.1 

89.6 

18.1 

3.4 

Sugar  beet  (roots)  . 

4320 

53 

8.8 

3.8 

72.9 

7.1 

7.8 

Potatoes  (tubers)  . 

3360 

46 

9.4 

1.1 

64.5 

2.4 

3.7 

Tobacco  (leaf)  .    . 

1800 

65 

3.5 

6.4 

73.8 

57.5 

15.0 

Tobacco  (stalk) 

3200 

32 

3.5 

2.0 

40.6 

10.5 

3.0 

Total  crop      .     . 

5000 

97 

7.0 

8.4 

114.4 

68.0 

18.0 

regulate  their  temperature  by  transpiration  (i.e.  exhalation  of 
water  vapor,  from  their  leaves)  just  as  animals  keep  their 
temperatures  normal  by  means  of  perspiration  from  their 
skins.  The  amount  of  water  thus  required  by  a  plant  is 
very  great.  So,  for  example,  it  takes  from  250  to  300  pounds 
of  water  to  produce  a  pound  of  dry  matter  in  the  corn  plant,  and 
in  the  clover  plant  from  500  to  600  pounds  of  water  are  neces- 
sary to  finally  obtain  a  pound  of  dry  material. 

The  fertility  of  the  soil  depends  upon  a  number  of  factors. 


THE  SOIL  203 

In  order  to  be  fertile  a  soil  must  first  of  all  contain  the  chemical 
elements  that  are  essential  for  plant  growth.  But  these  elements 
must  also  be  available  to  the  rootlets  of  the  plants  in  the  form  of 
suitable  soluble  compounds.  Now  since  nothing  can  pass  into 
the  roots  except  as  it  is  dissolved  in  the  soil  water,  it  is  clear  that 
plant  food  must  always  be  present  in  solution  in  the  water  of 
the  soil  in  sufficient  quantity  in  order  that  crops  may  thrive. 
Furthermore,  undesirable  bacteria  and  other  injurious  organ- 
isms must  not  be  present,  that  is  to  say,  the  soil  must  be  in 
proper  sanitary  condition.  Again,  a  sufficient  quantity  of  mois- 
ture, containing  carbon  dioxide  to  enhance  its  solvent  power, 
must  be  present  in  the  soil,  and  the  latter  must  be  sufficiently 
loose  to  enable  the  roots  to  penetrate  it  and  air  to  enter  and 
circulate  in  it.  At  the  same  time  soil  should  not  be  so  porous 
as  to  dry  out  too  rapidly.  Sandy  soils  commonly  present 
the  latter  defect.  As  has  already  been  stated,  the  solvent 
action  of  water  upon  the  mineral  matter  of  soils  is  rather  slow, 
even  when  the  water  is  charged  with  carbon  dioxide ;  and  so, 
though  a  soil  may  contain  a  great  abundance  of  the  elements 
necessary  for  plant  growth,  this  supply  is  often  not  avail- 
able in  sufficient  quantity  as  needed.  The  decaying  or- 
ganic matter  in  the  soil,  to  be  sure,  liberates  carbon  dioxide, 
which  helps  to  increase  the  solvent  power  of  the  soil  water,  at 
the  same  time  this  rotted  plant  material  furnishes  to  the  soil 
in  available  soluble  form  the  very  elements  that  are  essential 
for  the  growth  of  the  crop.  For  these  reasons  the  presence  of 
considerable  amounts  of  decomposing  vegetable  matter  is  essen- 
tial to  the  fertility  of  most  soils.  But  often  the  entire  supply 
of  plant  food  in  a  soil  is  insufficient,  and  so  it  is  necessary  to 
fertilize  the  land,  that  is,  to  add  material  to  it  which  contains 
abundant  plant  food  in  readily  soluble,  i.e.  available,  form. 
This  is  accomplished  by  treating  the  soil  with  manure  or 
commercial  artificial  fertilizers  that  contain  the  ingredients 


204  CHEMISTRY  AND  DAILY  LIFE 

which  are  lacking.  Thus  from  the  decomposition  of  mineral 
particles,  from  the  remains  of  roots  and  other  vegetable 
matter  left  on  the  soil,  as  well  as  from  manures  and  fertilizers 
used,  there  gradually  accumulates  a  considerable  supply  of 
material  that  serves  as  food  for  the  season's  crop,  which  as  it 
is  taken  from  the  land  in  turn  leaves  its  roots  and  stems  to 
decay,  and  so,  aided  by  additional  manure  and  fertilizer, 
furnishes  the  material  necessary  for  the  next  crop,  and  so  on. 
But  there  are  always  losses  of  plant  food  by  erosion,  the  leaching 
of  manure,  and  the  sale  of  grain,  sheep,  cattle,  hogs,  milk,  and 
other  products  from  the  farm.  These  constantly  cause  a  re- 
duction of  material  for  any  succeeding  year's  crop.  On  the 
other  hand,  there  may  be  very  substantial  gains  made, 
especially  of  desirable  compounds  of  nitrogen  and  carbon,  by 
raising  crops  that  absorb  nitrogen  from  the  atmosphere,  a 
process  which  is  accomplished  by  the  action  of  bacteria 
growing  on  the  roots.  Clover,  alfalfa,  beans,  peas,  as  well 
as  other  members  of  the  legume  family,  are  crops  of  this 
character.  It  is,  of  course,  not  always  easy  to  estimate  the 
extent  of  the  losses  which  a  soil  has  sustained,  especially  by 
erosion  and  waste ;  nor  is  it  simple  to  ascertain  the  gains  that 
have  been  made  by  growing  legume  crops. 

Usually,  the  organic  matter  and  essential  elements  present  in 
available  form,  together  with  the  soil  reaction,  are  the  most 
prominent  factors  that  are  to  be  considered  in  crop  produc- 
tion. The  humus  produced  by  the  decomposition  of  organic 
matter  in  the  soil  forms  a  coating  around  the  soil  grains.  It 
helps  to  bind  the  soil  grains  together  so  that  they  are  less 
readily  blown  about  by  winds.  It  also  increases  the  moisture- 
retaining  power  of  the  soil,  so  that  it  can  hold  from  two  to 
three  times  its  own  weight  of  water.  Again,  in  clay  soils  it 
lessens  the  tenacity  with  which  the  particles  of  the  soil  are 
held  together,  and  this  makes  it  easier  to  work  these  soils 


THE  SOIL  205 

properly.  Humus  is,  moreover,  a  storehouse  of  nitrogen 
compounds,  and  consequently  humus  soils  are  always  rich 
in  nitrogen.  By  the  slow  action  of  bacteria,  complex  nitrog- 
enous compounds  in  humus  are  successively  broken  down 
into  the  simple  compounds,  ammonia,  nitrites,  and  nitrates. 
The  nitrates  are  the  final  and  highest  oxidation  product.  They 
serve  as  a  source  of  nitrogen  for  the  growing  plants,  whose 
roots  absorb  the  nitrates  dissolved  in  the  soil  waters.  The 
process  by  which  ammonia  is  transformed  to  nitrates  in  soils 
is  called  nitrification.  The  amount  of  nitrates  in  the  soil 
waters  at  any  one  time  is  very  small,  yet  it  is  very  important, 
for  most  plants  take  their  supply  of  nitrogen  from  the  soil 
in  this  form.  Plants  utilize  the  nitrogen  thus  obtained  in 
building  up  those  wry  important  and  complex  constituents,  the 
proteins. 

The  preparation  of  the  available  supply  of  nitrogen  for 
plants  by  the  bacteria  of  the  soil  forms  one  of  the  most  inter- 
esting chapters  in  the  story  of  the  feeding  of  crops.  When 
plants  die,  their  roots,  stalks,  and  leaves  are  returned  to  the 
soil,  where  their  decomposition  is  brought  about  by  molds, 
bacteria,  and  other  low  forms  of  life.  Much  plant  material 
is  fed  to  animals,  but  even  then  a  large  residue  of  unoxidized 
matter  is  returned  to  the  soil  as  manure.  This  vegetable 
matter  or  animal  refuse  is  attacked  by  putrefactive  bacteria, 
which  reduce  the  proteins  to  simpler  compounds.  Still 
other  bacteria  convert  these  into  ammonia,  which  really 
represents  the  first  step  in  the  process  of  nitrification,  i.e. 
nitrate  making.  Ammonia  is  changed  to  nitrites  by  the 
nitrite  bacteria,  and  finally  the  nitrate  bacteria  effect  the 
oxidation  of  nitrites  to  nitrates.  The  bacteria  do  not  really 
produce  the  nitrites  and  nitrates,  but  they  oxidize  ammonia 
to  nitrous  and  nitric  acid.  As  these  acids  accumulate,  they 
stop  further  action  on  part  of  the  bacteria ;  hence  the  neces- 


206 


CHEMISTRY  AND   DAILY  LIFE 


sity  of  having  limestone  or  air-slaked  lime  present  in  the  soil 
to  neutralize  the  acids  as  they  form.  In  this  way  calcium 
nitrate  is  left  in  the  soil  as  the  final  product  of  nitrification.  In 
the  form  of  nitrates,  the  nitrogen  then  passes  from  the  soil 
into  the  plant,  where  it  is  utilized  in  building  up  proteins. 
These  are  then  returned  to  the  soil  direct,  or  they  are  first 
fed  to  animals,  in  which  case  the  nitrogen  is  excreted  in  sim- 
pler compounds  (urea,  uric,  and  hippuric  acids)  in  the  urine 
and  more  complex  ones  in  the  feces.  When  returned  to  the 

soil,  all  of  these  compounds  are 
first  converted  to  ammonia  and 
finally  again  to  nitrates,  and  thus 
the  nitrogen  cycle  completes  itself 
over  and  over  again  as  long  as  the 
sun  furnishes  the  necessary  energy 
for  plant  growth. 

While  plants  in  general  do  not 
get  their  nitrogen  supply  direct 
from  the  air,  it  has  already  been 
mentioned  that  legumes  are  able 
to  store  up  nitrogen  from  the 
air  in  little  nodules  on  their 
roots,  with  the  aid  of  certain 
bacteria.  So,  for  example,  the 
nodules  on  the  roots  of  red 
clover,  beans,  and  cowpeas  are  a 
matter  of  common  observation. 
In  these  nodules  are  bacteria 
which  take  the  nitrogen  direct 
FIG.  76.— Nodules  on  the  roots  from  the  air,  and  then  give  it 

of  a  soy  bean.  over  to  the  plant  in  the  form  of 

nitrogenous  compounds.  This  process  of  converting  the 
nitrogen  of  the  air  into  nitrogenous  compounds  is  commonly 


THE  SOIL  207 

spoken  of  as  the  fixation  of  nitrogen.  The  plant  in  turn 
gives  the  bacteria  such  food  as  sugar  to  live  on.  When  the 
plant  dies,  there  is  left  in  these  nodules  on  the  roots  a  con- 
siderable supply  of  nitrogen,  which  upon  subsequent  nitrifi- 
cation becomes  available  for  the  next  crop  Thus  it  is  that 
the  growing  of  a  good  crop  of  cowpeas  or  soy  beans  will  usually 
leave  enough  available  nitrogen  in  the  soil  for  a  good  crop  of 
cotton  or  corn.  Consequently  raising  a  crop  of  a  legume  in  a 
rotation  is  one  of  the  most  important  methods  of  maintaining  the 
available  nitrogen  supply  of  the  soil. 

Soils  are  spoken  of  as  acid,  alkaline,  or  neutral  according  to 
their  reaction  toward  litmus  pamper.  Acid  soils  are  unsuitable 
for  the  successful  growth  of  legumes,  and  it  is  therefore  usu- 
ally desirable  to  correct  such  acidity  by  an  application  of 
fresh  lime,  ground  limestone,  or  marl.  It  is  better  to  use 
old,  thoroughly  air-slaked  lime,  rather  than  fresh  quick- 
lime, for  the  latter  has  caustic  properties.  A  ton  of  finely 
pulverized  limestone  per  acre  once  in  five  years  is  commonly 
not  too  much. 

The  amount  of  phosphorus  in  most  soils  is  generally  small, 
being  from  0.02  to  0.1  per  cent.  All  crops  take  phosphorus 
from  the  soil,  in  which  this  element  is  present  as  phosphates. 
Plants  store  up  phosphorus,  especially  in  their  seeds.  The 
supply  of  phosphates  in  the  soil  can  consequently  be  main- 
tained by  lessening  the  sale  of  seed,  or  crops,  or  by  adding 
suitable  phosphorus  containing  fertilizers.  If  a  farmer  buys 
plentifully  of  feeds,  especially  bran,  for  his  stock  and  sells 
only  milk  and  animals,  he  may  not  need  to  purchase  phos- 
phorus in  the  form  of  commercial  fertilizer.  Indeed,  the 
soils  of  farms  of  dairy  states,  where  milk  and  cream  are  sold  and 
feeds  are  purchased,  may  actually  show  a  gain  of  phosphorus. 
Raw  rock  phosphate,  also  called  "  floats,"  is  a  cheap  commer- 
cial fertilizer  for  soils  deficient  in  phosphorus.  When  used 


208  CHEMISTRY  AND  DAILY  LIFE 

with  organic  material,  although  rather  slow  in  becoming 
available  on  account  of  the  fact  that  its  phosphates  do  not 
dissolve  very  readily,  it  nevertheless  gives  good  results. 
Superphosphate,  or  acid  phosphate  (which,  as  has  been  stated 
in  Chapter  VII,  is  made  by  treating  bones  or  phosphate  rock 
with  sulphuric  acid),  dissolves  far  more  readily  and  hence  is 
immediately  available  to  plants.  It  should  be  used  when  a 
supply  of  organic  matter  is  not  at  hand. 

There  is  usually  a  sufficient  amount  of  available  potassium 
in  soils.  This  is  especially  true  of  clay  soils,  which  are  rich 
in  feldspars.  And  so  when  these  soils  are  furnished  with 
plenty  of  organic  matter  that  gives  off  carbon  dioxide  as  it 
decomposes,  thereby  increasing  the  solvent  action  of  the  soil 
water  on  the  feldspathic  constituents,  an  ample  supply  of 
potassium  is  furnished  to  the  rootlets  of  the  growing  crop. 
Some  soils,  like  sands  and  marshes,  are  deficient  in  potassium. 
To  these  it  should  be  added  at  the  rate  of  fifty  to  one 
hundred  pounds  of  potassium  chloride  or  potassium  sulphate 
per  acre. 

Although  the  quantity  of  sulphur  in  soils  is  usually  low, 
being  about  as  low  as  that  of  phosphorus,  it  is  replenished 
to  a  considerable  extent  during  the  year  by  rains.  These 
carry  sulphur  dioxide  down  in  solution  from  the  atmosphere. 
The  sulphur  dioxide  has  come  into  the  air  mainly  from  the 
burning  of  coal.  For  some  crops  which  need  much  sulphur, 
like  onions,  cabbage,  turnips,  and  rutabagas,  additional  sulphur 
in  the  form  of  gypsum,  calcium  sulphate,  is  advantageous. 
From  100  to  200  pounds  per  acre  is  a  good  application. 

It  has  already  been  stated  that  the  soil  must  be  in  proper 
mechanical  condition  so  that  it  will  readily  hold  the  proper 
amount  of  water,  permit  air  to  circulate  in  it,  and  allow  the 
roots  to  penetrate  it.  Proper  tilth  of  the  soil,  that  is  to  say, 
proper  mechanical  working  of  the  soil  with  the  plow,  spade, 


THE  SOIL  209 

hoe,  harrow,  roller,  etc.,  is  of  great  importance.  While  it  is 
desirable  that  the  particles  of  the  soil  be  sufficiently  fine,  it 
must  also  be  remembered  that  they  may  be  so  fine  and  closely 
compacted  together  that  neither  air  nor  root  hairs  can  gain 
entrance.  This  condition  is  just  as  unfavorable  as  a  coarse, 
lumpy  soil.  In  either  case  the  water  storage  capacity  is 
decreased.  From  soils  that  are  too  loose  and  porous,  moisture 
drains  away,  and  the  air  circulates  so  freely  in  them  that  they 
dry  out  too  rapidly.  It  has  already  been  stated  that  this  is 
a  common  defect  of  sandy  soils.  By  the  force  of  capillarity, 
or  capillary  attraction,  water  rises  in  tubes  of  small  bore  or 
between  particles  of  solid  substances.  Fine-grained  soils,  of 
which  clay  soils  are  an  excellent  example,  have  small  pores  or 
spaces  between  their  particles,  and  hence  water  will  rise  from 
below  and  be  nearer  to  the  surface  in  these  soils  than  in  those 
of  coarser  grain.  It  is  indeed  possible  to  aid  the  upward  capil- 
lary movement  of  water  so  that  in  a  dry  season,  when  the  seeds 
have  been  planted,  moisture  will  be  drawn  to  them  from  be- 
low. This  is  accomplished  by  rolling  the  ground,  for  roll- 
ing forces  the  particles  of  soil  closer  together  and  thus  a 
stronger  upward  movement  of  water  by  capillarity  results. 
Much  water  that  has  thus  been  drawn  up  by  capillarity  is  lost  by 
evaporation  at  the  surface  of  the  soil.  This  loss  can  be  greatly 
reduced  by  covering  the  surface  with  a  protecting  layer  or 
soil  mulch.  So  if  the  surface  of  the  soil  to  the  depth  of  two 
or  three  inches  is  thoroughly  stirred  on  a  dry,  windy  day, 
the  dry  layer  that  is  thus  formed  becomes  an  effective  barrier 
against  large  losses  of  moisture  from  below.  In  regions 
where  rainfall  is  light  this  practice  is  of  the  very  greatest 
importance.  It  is  upon  this  principle  that  so-called  dry 
fanning  is  based. 

In  speaking  of  soil  waters,  the  terms  gravitational  water, 
capillary  water,  and  hydroscopic  water  are  often  used.     Their 


210  CHEMISTRY  AND  DAILY  LIFE 

meaning  will  be  clear  from  the  following  experiment.  If  the 
neck  of  a  funnel  be  stoppered,  and  the  funnel  be  filled  with 
soil,  and  then  water  poured  on  till  the  funnel  is  brim  full, 
the  soil  will  be  in  a  saturated  condition.  If  now  the  stopper 
is-  removed,  a  considerable  portion  of  the  water  will  drain 
off ;  this  is  called  gravitational  water,  for  it  runs  off  because 
of  the  action  of  the  force  of  gravitation.  If  the  lower  end 
of  the  funnel  is  now  stoppered  again  and  the  whole  allowed 
to  stand,  with  the  upper  surface  exposed,  a  large  part  of  the 
moisture  retained  by  the  soil  will  rise  up  to  replace  that 
which  is  lost  at  the  surface  by  gradual  evaporation.  This 
upward  movement  of  the  water  in  the  soil  is  due  to  capillarity, 
and  the  water  held  and  moved  in  this  way  is  termed  capil- 
lary water.  If  the  funnel  is  thus  allowed  to  remain  exposed 
to  the  air  for  several  days  or  weeks,  the  soil  it  contains  will 
become  dry.  But  if  a  portion  of  this  apparently  dry  soil  be 
weighed  out  and  then  heated  at  the  temperature  of  a  boiling 
water  bath,  100°  C.,  it  loses  still  more  moisture.  The  water 
thus  expelled  is  called  hydroscopic  water.  It  is  obvious 
that  it  is  held  more  tightly  by  the  soil  particles  than  the 
capillary  water. 

The  removal  of  gravitational  water  by  proper  natural  or 
artificial  underdraining  is  necessary  because,  if  it  remains  in 
the  soil,  the  latter  becomes  water-logged,  and  so  displaces 
the  air  which  is  necessary  in  the  soil  for  the  growing  roots. 
Drainage  lowers  the  water  level  in  the  soil,  causing  roots  to 
penetrate  deeper  for  moisture,  and  consequently  their  feeding 
ground  is  increased.  This  helps  them  to  withstand  drought. 
The  amount  of  moisture  in  a  soil  must  be  taken  into  consider- 
ation in  determining  whether  it  is  an  opportune  time  to  work 
the  soil  or  not.  So,  for  instance,  if  heavy  clay  soils  are  worked 
when  wet,  the  particles  are  forced  close  together  and  "  pud- 
dling "  is  the  result.  This  is  a  brickmaker's  term.  In  making 


THE  SOIL  211 

brick  the  first  effort  is  to  destroy  the  granular  texture  of  the 
clay,  which  is  accomplished  by  wetting  and  working  it.  If 
this  is  done  with  clay  soil,  it  obviously  will  be  left  very  com- 
pact and  hard  when  it  dries.  Such  a  condition,  once  brought 


FIG.  77.  —  Cracked  soil.     Large  losses  of  water  will  result  from  such  a 
condition. 

about  by  working  the  clay  soil  when  too  wet,  may  last  for 
a  number  of  years,  and  so  it  is  wise  for  the  farmer  not  to  get 
his  clay  fields  puddled.  When  land  breaks  up  cloddy,  it  is 
desirable  that  it  be  plowed  long  before  planting  in  order  that 
freezing,  thawing,  and  weathering  may  break  up  the  clods 
and  make  them  loose  and  mellow.  This  requires  time,  but 
for  best  results  long  exposure  to  the  weather  will  pay.  The 


212  CHEMISTRY  AND   DAILY  LIFE 

effect  of  humus  on  fine-grained  soils,  such  as  clays,  is  to 
divide  the  particles  and  so  lessen  the  tendency  to  puddle. 
In  sandy  soils,  humus  tends  to  cement  the  grains  of  sand 
together  more  firmly,  a  result  that  could  not  be  secured  by 
mere  films  of  water  around  such  coarse  particles. 

The  temperature  of  soils  is  affected  by  their  power  to  ab- 
sorb heat  from  the  rays  of  the  sun.  The  readiness  with 
which  heat  is  thus  absorbed  is  greatly  influenced  by  the  color 
of  the  soil.  Thus  dark-colored  soils  absorb  heat  readily  and 
so  warm  up  relatively  rapidly.  They  are  consequently 
called  warm  soils.  On  the  other  hand,  light-colored  soils  do 
not  absorb  heat  so  readily  as  dark-colored  ones  of  equal 
moisture  content,  and  they  consequently  do  not  warm  so 
quickly.  They  are  called  cold  soils.  It  must  be  borne  in 
mind,  however,  that  the  amount  of  moisture  in  the  soil  is  the 
most  important  factor  in  determining  the  rate  at  which  it  will 
warm  up,  for  it  takes  large  amounts  of  heat  to  evaporate 
water,  and  so  dry  soils  always  warm  up  more  rapidly  than  wet 
ones,  regardless  of  their  color  or  composition.  Barefooted  boys 
well  know  that  dry  sand  and  fine  road  dust  become  warm 
more  quickly  than  a  wet  soil.  Indeed,  the  evaporation  of 
water  from  the  soil  cools  the  latter,  just  as  the  evaporation 
of  sweat  cools  the  animal  body.  Dark-colored,  sandy  soils 
warm  up  earliest  in  spring  because  the  gravitational  water  soon 
drains  out  of  them  and  they  readily  absorb  heat  from  the 
sun's  rays.  Such  soils,  then,  are  most  suitable  for  market 
gardening  or  early  spring  crops. 


THE  SOIL  213 


QUESTIONS 

1.  From  what  is  soil  made,  and  what  are  the  agencies  active  in 
its  formation  ?    What  is  a  glacier  ? 

2.  How  are  peat  bogs  formed  ? 

3.  What  is  the  difference  between  sedentary  and  transported 
soils  ? 

4.  What  is  the  difference  between  a  sandy  soil  and  a  clay  soil  ? 
What  is  humus  ? 

5.  Name  the  essential  elements  needed  for  crop  production. 

6.  About  how  much  phosphorus  is  there  in  a  soil,  and  how  many 
crops  of  wheat  would  it  produce  ? 

7.  How  much  water  is  required  to  make  a  pound  of  dry  matter 
in  a  corn  plant  ? 

8.  Why  is  it  necessary  to  have  plenty  of  organic  matter  in  the 
soil? 

9.  How  would  you  maintain  the  nitrogen  content  of  soils  ? 

10.  What  may  the  reaction  of  the  soil  be,  and  what  should  be  the 
proper  reaction  for  the  growth  of  legumes  ? 

11.  What  is  meant  by  the  puddling  of  clay?    What  is  the  in- 
fluence of  humus  on  the  water-holding  power  of  a  soil  ?    Distinguish 
between  capillary  and  gravitational  water. 

12.  How  does  drainage  help  a  plant  in  a  season  of  drought  ? 


CHAPTER   XV 
COMMERCIAL   FERTILIZERS 

COMMERCIAL  fertilizers  are  manufactured  plant  foods. 
They  are  usually  kept  for  sale  at  warehouses  and  seed  stores. 
About  $100,000,000  is  spent  annually  in  the  purchase  of 
fertilizers  in  the  United  States  and  probably  one-half  of 
this  money  is  thrown  away.  This  is  not  an  argument 
against  the  use  of  commercial  fertilizers,  but  it  does  mean 
that  they  should  be  purchased  with  proper  judgment,  and 
not  used  at  all  until  trials  have  shown  that  they  are  actually 
necessary. 

Experimental  investigations  and  common  experience  have 
shown  that  material  increases  in  the  yield  of  the  land  have 
in  most  cases  been  obtained  by  adding  to  the  soil  but  three 
of  the  essential  elements  necessary  for  plant  growth  ;  'namely, 
nitrogen,  phosphorus,  and  potassium.  These  elements,  it 
is  to  be  recalled,  are  not  applied  in  the  free  or  uncombined 
state,  but  in  the  form  of  compounds,  usually  salts,  that  will 
dissolve  in  the  soil  waters,  so  that  they  can  be  absorbed  by  the 
rootlets  of  the  growing  crop.  In  consequence  of  the  results 
of  experience,  then,  commercial  fertilizers  as  placed  on  the 
market  to-day  contain  as  their  essential  ingredients  only 
nitrogen,  phosphorus,  and  potassium  in  the  form  of  mixtures 
of  salts  or  other  compounds  of  these  elements ;  and  thus  it 
is  that  the  nitrogen,  phosphorus,  and  potassium  in  a  commercial 
fertilizer  are  the  only  materials  which  give  that  fertilizer  value. 
It  should  be  remembered,  however,  that  equally  good  results 
are  sometimes  secured  by  applying  to  the  land  dressings  that 

214 


COMMERCIAL  FERTILIZERS 


215 


FIG.  78.  —  Effect  of  fertilizers  on  a  crop  of  potatoes.     (^4)   Complete  fertilizer 
used.     (B)   No  fertilizer  used. 


216  CHEMISTRY   AND  DAILY  LIFE 

do  not  contain  any  of  the  three  elements  just  mentioned. 
So,  for  example,  lime  or  limestone  and  gypsum  are  fre- 
quently beneficial.  The  benefit  derived  from  lime  is  usually 
due  to  its  basic  properties,  which  cause  a  neutral  or  alkaline 
reaction  of  the  soil.  Gypsum,  on  the  other  hand,  acts  as  a 
source  of  sulphur,  and  also  produces  physical  changes  in  the 
soil. 

Commercial  fertilizers  are  made  from  a  few  basal  materials 
which  are  articles  of  commerce.  A  so-called  complete  ferti- 
lizer consists  of  two  or  more  such  basal  materials  mixed  to- 
gether so  as  to  give  the  desired  percentage  content  of  nitro- 
gen, phosphorus,  and  potassium.  These  basal  materials  are 
derived  (1)  from  inorganic  or  mineral  matter,  and  (2)  from 
organic  matter,  that  is  to  say,  from  animal  or  vegetable  material. 
So,  for  example,  as  sources  of  nitrogen,  the  inorganic  salts, 
ammonium  sulphate  and  sodium  nitrate,  and  organic  mate- 
rials like  dried  blood,  meat  scraps,  tankage,  fish  scrap,  and 
cotton-seed  meal  are  in  common  use.  As  sources  of  phos- 
phorus, phosphate  rock  and  basic  slag,  which  are  inorganic, 
and  bones  and  guano,  which  are  organic,  are  utilized.  Fi- 
nally, as  sources  of  potassium,  potassium  chloride,  potassium 
sulphate,  and  kainite,  all  of  which  come  from  the  Stassfurt 
salt  deposits,  are  employed.  All  of  these  materials  will  now 
be  considered  more  in  detail. 

Among  the  nitrogenous  fertilizers  ammonium  sulphate, 
(NH4)2SO4,  also  popularly  called  "  sulphate  of  ammonia,"  is 
used  to  a  considerable  extent.  This  salt  has  already  been 
mentioned  in  Chapter  IV.  It  is  a  by-product  of  the  manu- 
facture of  illuminating  gas  from  coal,  also  of  the  dry  distilla- 
tion of  bones  in  the  manufacture  of  bone  black.  Ammonium 
sulphate  is  a  very  concentrated  fertilizer,  containing  20 
per  cent  of  nitrogen.  It  is  copiously  soluble  in  water,  does  not 
readily  leach  out  of  the  soil,  and  very  quickly  undergoes 


COMMERCIAL  FERTILIZERS  217 

nitrification,  that  is,  conversion  into  nitrates.  Sodium  ni- 
trate, NaNO3,  also  called  nitrate  of  soda,  has  been  described 
in  Chapter  X.  It  occurs  as  Chili  saltpeter  in  extensive  de- 
posits in  the  rainless  districts  of  western  South  America. 
The  natural  material  from  the  saltpeter  beds  contains  a 
large  amount  of  common  salt.  This,  however,  is  practically 
removed  from  the  product  before  it  is  placed  on  the  market, 
so  that  as  sold  it  is  a  crude  nitrate  of  soda  containing  from  15 
to  16  per  cent  of  nitrogen.  Nitrate  of  soda  is  readily  soluble 
in  water  and  easily  leached  from  the  soil.  It  should  conse- 
quently be  applied  just  before  planting  or  after  the  plant  has 
possession  of  the  soil.  Fifty  to  one  hundred  pounds  per  acre 
is  a  proper  application.  Dried  blood,  meat  scraps,  and  tank- 
age come  from  the  slaughterhouses.  Dried  blood  is  simply 
blood  of  the  slaughtered  animals  dried  and  ground.  Like  all 
organic  nitrogenous  fertilizers,  it  is  insoluble  in  water ;  but  it 
ferments  readily  in  the  soil  and  yields  its  nitrogen  in  soluble 
form  to  the  growing  plant.  Dried  blood  contains  from  13 
to  14  per  cent  of  nitrogen,  while  meat  scraps  contain  variable 
amounts  of  nitrogen,  usually  from  4  to  10  per  cent.  The 
value  of  fish  as  a  fertilizer  was  known  to  our  American  Indi- 
ans. Squanto,  an  Indian,  taught  the  New  England  settlers 
that  they  could  increase  the  yield  of  corn  by  putting  a  fish 
under  each  hill.  This  gave  the  grain  the  two  elements  it 
needed  most,  phosphorus  and  nitrogen.  To-day  fish  ferti- 
lizers are  made  in  large  amounts  from  rough  fish  and  fish 
oft'al  on  the  Atlantic  coast  and  the  Great  Lakes.  Cotton- 
seed meal  is  obtained  by  removing  the  hulls  and  oil  from 
cotton  seed.  The  residue  is  then  ground  and  put  on  the 
market.  It  is  extensively  used  as  a  fertilizer  in  the  south. 
There  are  still  other  nitrogenous  fertilizers  like  waste  leather, 
hoof  and  horn  meal,  hair  from  the  slaughterhouses,  and 
wool  waste  from  the  woolen  mills.  The  chemical  nature 


218  CHEMISTRY  AND   DAILY  LIFE 

of  these 'has  already  been  described  in  Chapters  IX  and 
XIII.  All  of  these  materials  decompose  so  slowly  in  the 
soil  that  many  states  have  passed  laws  prohibiting  their 
sale  as  fertilizers.  In  ordinary  farming  it  is  seldom  profit- 
able to  purchase  nitrogenous  fertilizers,  for  the  nitrogen  supply 
of  the  soil  can  be  maintained  by  means  of  farm  manure  and 
the  proper  use  of  legume  crops  in  rotation,  as  already  stated 
in  Chapter  XIV.  Such  crops  as  the  clovers,  peas,  and  beans 
are  aids  to  the  farmer  as  nitrogen  gatherers,  especially  if  he 
occasionally  plows  under  a  goodly  part  of  the  plant.  In 
intensive  farming,  like  market  gardening,  it  will  be  necessary 
to  make  liberal  use  of  nitrogenous  fertilizers  of  commercial 
origin. 

Since  three-fourths  of  the  phosphorus  absorbed  from  the 
soil  is  deposited  in  the  grain  of  the  crop  and  therefore  ordi- 
narily sold  from  the  farm,  it  is  clear  that  phosphatic  ferti- 
lizers are  of  fundamental  importance.  In  the  soil,  phosphorus 
occurs  as  the  phosphates  of  calcium,  magnesium,  and  iron. 
As  already  pointed  out  in  Chapter  VII,  phosphates  are  salts 
of  phosphoric  acid,  H3PO4.  In  all  the  important  commercial 
phosphate  fertilizers,  including  phosphate  rock,  bones,  basic 
slag,  and  guano,  phosphorus  is  present  as  phosphates  formed 
by  the  combination  of  phosphoric  acid,  H3PO4,  with  lime,  CaO. 
These  are  phosphates  of  calcium,  commonly  spoken  of  as 
phosphates  of  lime.  With  lime,  phosphoric  acid  forms  three 
important  compounds  :  (1)  insoluble  phosphate  of  lime,  which  is 
tricalcium  phosphate,  Ca3(PO4)2 ;  (2)  soluble  phosphate  of  lime, 
which  is  monocalcium  phosphate,  CaH4(PO4)2 ;  and  (3)  reverted 
phosphate  of  lime,  which  is  dicalcium  phosphate,  Ca2H2(PO4)2. 
The  first  of  these,  as  its  name  indicates,  is  almost  insoluble 
in  water  and  hence  is  not  readily  available  to  plants.  Ground 
bone,  guano,  and  floats  contain  their  phosphorus  in  this  form. 
Ground  bone,  or  bone  meal,  is  a  product  of  the  packing  houses, 


COMMERCIAL  FERTILIZERS 


219 


glue  factories,  and  soap  works,  the  raw  material  being  the 
bones  of  farm  animals.  The  bones  are  either  ground 
directly  or  after  they  have  been  steamed  and  dried.  In  the 
latter  case  they  are  called  steamed  bone.  Raw  bone  con- 
tains 2.5  per  cent  of  nitrogen  and  11  per  cent  of  phosphorus. 
It  is  more  effective  when  finely  ground  than  when  coarse ; 
furthermore,  raw  bone  decomposes  more  slowly  in  the  soil 
than  steamed  bone,  because  the  fat  has  been  removed  from 
the  latter.  Guano,  a  highly  prized  but  comparatively  rare 
fertilizer,  consists  of  the  excrements  and  remains  of  sea  fowls, 
which  have  accumulated  in  certain  localities  along  the  west 
coast  of  South  America.  It  contains  nitrogen,  potassium, 
and  phosphorus,  the  latter  amounting  to  from  4  to  8  per  cent. 
The  phosphorus  in  guano  has  come  from  the  skeletons  of 
of  the  birds.  Floats  is  the  term  applied  to  the  finely  ground 


FIG.  79.  —  Phosphate-rock  mining  in  Florida. 

crude  phosphate  rock  found  in  Tennessee,  the  Carolinas, 
Florida,  Georgia,  and  other  Southern  states.  It  has  recently 
also  been  discovered  in  considerable  beds  in  Utah  and 


220  CHEMISTRY  AND  DAILY  LIFE 

Wyoming.  It  contains  from  11  to  13  per  cent  of  phosphorus 
and  is  the  chief  source  and  also  the  cheapest  source  of  phos- 
phorus supply  on  the  market.  Recent  investigations  have 
shown  that  when  used  with  sufficient  organic  matter,  such 
as  farm  manure  or  green  manure,  ground  phosphate  rock 
has  high  fertilizing  power,  for  the  organic  matter  on  decom- 
posing furnishes  carbonic  acid,  which  aids  in  dissolving  the 
tricalcium  phosphate,  thus  making  it  available.  Soluble 
phosphate  of  lime  is  also  known  as  "  one  lime  phosphate," 
acid  phosphate,  acidulated  rock,  superphosphate,  etc.  It  is 
made  by  treating  bones  or  phosphate  rock  with  sulphuric 
acid,  as  stated  in  Chapter  VII,  where  the  chemical  equation 
explaining  its  formation  is  given.  Because  of  its  solubility 
in  water,  this  fertilizer  contains  the  phosphorus  in  the  most 
available  form  for  direct  use  by  the  plant.  A  good  sample  con- 
tains about  7  per  cent  of  phosphorus,  or  only  about  half  as 
much  as  a  good  sample  of  rock  phosphate.  Furthermore, 
a  ton  of  the  material  contains  about  half  a  ton  of  gypsum. 
The  latter  is  formed  simultaneously  when  the  sulphuric 
acid  acts  on  tricalcium  phosphate.  Though  readily  soluble 
in  water  superphosphate  is  not  leached  out  of  the  soil,  for  the 
lime  an<d  iron  in  the  soil  can  form  insoluble  phosphates  with 
it.  In  the  process  of  making  acid  phosphate  the  whole 
of  the  insoluble  phosphate  is  generally  not  acted  upon.  The 
tricalcium  phosphate  thus  remaining  when  left  with  large 
quantities  of  the  monocalcium  phosphate  forms  dicalcium 
phosphate,  thus : 

Ca3(PO4)2       +      CaH4(PO4)2     =    2  Ca2H2(PO4)2 

tricalcium  phosphate  monocalcium  phos-         dicalcium  phosphate 

from  bone  or  phosphate        phate,  "acid  phos-        "reverted  phosphate" 
rock  phate " 

It  is  clear,  then,  that  the  dicalcium  phosphate  formed  is  less 
atid  than  the  monocalcium  phosphate,  i.e.  the  latter  has 


COMMERCIAL  FERTILIZERS  221 

"  reverted  "  somewhat.  Hence  it  is  known  as  "  reverted 
phosphate."  Though  almost  insoluble  in  water,  it  dissolves 
in  water  containing  carbon  dioxide  and  hence  is  readily  as- 
similated by  plants.  As  stated  in  Chapter  XI,  a  phosphate 
fertilizer  is  produced  in  the  manufacture  of  steel.  This 
material  is  popularly  called  basic  slag,  its  composition  being 
about  Ca5P2SiOi2.  Though  it  was  formerly  thrown  away, 
its  value  as  a  fertilizer  is  now  duly  recognized.  It  contains 
from  6.5  to  8.5  per  cent  of  phosphorus  in  a  somewhat  different 
form  from  that  in  the  other  phosphates  just  described,  as 
the  formula  given  indicates.  It  should  be  finely  ground,  for 
it  is  difficultly  soluble  in  the  soil  water.  The  fact  that  it  is 
rich  in  lime  makes  it  specially  desirable  for  use  on  acid  soils. 
Most  of  the  basic  slag  on  the  market  is  imported  from  England, 
but  it  is  not  unlikely  that  more  will  soon  be  made  in  the 
United  States,  as  iron  ores  of  high  phosphate  content  are  used 
in  the  iron  and  steel  industry. 

The  potash  fertilizers  are  commonly  considered  as  of  less 
importance  than  either  the  nitrogenous  or  phosphatic  fer- 
tilizers, for  potassium  compounds  are  usually  more  abundant 
in  the  soil  than  either  nitrogen-bearing  compounds  or  phos- 
phates. Moreover,  though  most  crops  remove  more  potassium 
than  phosphorus,  the  former  element  is  more  liable  to  be  re- 
turned to  the  soil  than  the  latter.  Potassium  is  more  abundant 
in  the  stems  and  leaves  of  plants,  and  as  these  are  the  parts 
that  are  generally  returned  to  the  land  in  the  form  of  manure, 
the  supply  of  potassium  is  constantly  being  replenished. 
On  the  other  hand,  potassium  is  a  very  necessary  constituent 
of  fertilizers  intended  for  light  sandy  soils,  for  marsh  land,  and 
for  fields  that  are  to  produce  crops  which  consume  large  quan- 
tities of  potassium,  like  potatoes,  tobacco,  and  fleshy  roots.  Pot- 
ash fertilizers  can  be  applied  in  the  fall  on  heavy  clay  soils,  or 
in  the  spring  on  sandy  soils.  As  stated  in  Chapter  XIV,  clays 


222  CHEMISTRY   AND   DAILY  LIFE 

generally  do  not  need  potash  fertilizers  if  well  supplied  with 
organic  matter.  The  potassium  salts  used  as  fertilizers  have 
already  been  described  in  Chapter  X.  They  come  from  the 
Stassfurt  mines.  So  the  chloride  KC1,  also  called  the  muriate 
of  potash,  contains  about  47  per  cent  of  potassium,  which  is 
combined  with  chlorine,  as  the  formula  indicates.  This  salt 
can  be  used  on  all  crops  except  a  few  like  tobaccco,  sugar 
beets,  and  potatoes,  which  appear  to  be  injured  by  the  chlo- 
rine present.  Potassium  sulphate,  K2SO4,  also  called  sul- 
phate of  potash,  contains  about  44  Per  cent  °f  potassium,  and 
is  of  special  value  for  those  crops  that  are  injured  by  the 
chloride,  as  just  mentioned.  Kainite  (see  Chapter  X),  the 
most  common  of  the  Stassfurt  fertilizers,  is  essentially  a  double 
salt  of  potassium  chloride  and  magnesium  sulphate.  It  con- 
tains from  10  to  12  per  cent  of  potassium  as  chloride  and  sul- 
phate. It  is  thus  a  low-grade  potash  fertilizer;  and  while 
cheap  per  ton,  it  really  costs  more  than  the  muriate  or  sul- 
phate, for  these  are  so  much  richer  in  potassium.  For  many 
years  wood  ashes  were  the  sole  source  of  potassium  for 
fertilizing  purposes,  but  since  the  introduction  of  the  Stass- 
furt salts,  ashes  appear  much  less  on-  the  market.  When 
unleached,  ashes  contain  from  2  to  7  per  cent  of  potassium  and 
hence  are  valuable.  Furthermore,  ashes  contain  the  potas- 
sium as  carbonate,  K2CO3,  and  also  carbonate  of  lime,  CaCO3, 
both  of  which  are  excellent  for  neutralizing,  that  is,  "  correct- 
ing," soil  acidity. 

A  number  of  substances  like  lime,  gypsum,  and  common  salt 
are  beneficial  to  the  land  under  certain  conditions,  but  they  are 
generally  not  considered  as  important  sources  of  plant  food, 
and  so  are  frequently  termed  indirect  fertilizers.  There  are 
but  few  if  any  soils  that  do  not  contain  enough  lime  to  supply 
the  needs  of  the  plant,  and  so  the  value  of  lime  as  a  fertilizer 
is  indirect.  It  corrects  acidity,  acts  upon  other  compounds 


COMMERCIAL  FERTILIZERS  223 

so  as  to  liberate  soluble  potassium  salts,  and  helps  bacterial 
life  in  the  soil.  By  keeping  the  soil  neutral,  it  creates  a 
proper  home  for  many  microorganisms  which  help  to  make 
plant  food  available.  Lime  for  agricultural  purposes  is 
put  on  the  market  as  caustic  or  burned  lime,  CaO ;  air-slaked 
lime  or  carbonate  of  lime,  CaCO3 ;  ground  limestone  rock ; 
ground  clam  or  oyster  shells,  CaCO3 ;  and  also  as  beet  sugar 
refuse.  The  chemical  nature  of  lime,  limestone,  or  calcium 
carbonate,  and  gypsum  has  already  been  sufficiently  described 
in  Chapters  IX  and  X.  Air-slaked  lime  is  quicklime  which 
has  again  been  converted  to  the  carbonate,  CaCO3,  by  ex- 
posure to  the  air.  When  caustic  lime  is  used  on  the  land 
it  must  be  applied  writh  care,  as  already  stated  in  Chapter 
XIV.  Finely  ground  limestone  is  coming  into  general  favor, 
and  when  it  can  be  obtained  at  a  sufficiently  low  cost,  it  is 
undoubtedly  the  safest  form  in  which  to  apply  lime,  espe- 
cially by  the  inexperienced.  Lime  should  be  spread  over 
the  surface  and  then  incorporated  with  the  upper  two  to 
four  inches  of  the  soil.  The  clovers  and  legumes  in  general 
require  more  lime  than  do  the  cereals,  for  they  are  much  more 
sensitive  to  the  acidity  of  the  soil.  A  ton  per  acre  every  four 
or  five  years  is  a  good  application  of  limestone.  Gypsum, 
land  plaster,  CaSO4 .  2  H2O,  has  given  excellent  results  with 
clovers  and  legume  plants.  It  is  also  a  cheap  source  of  sul- 
phur, which  is  low  in  amount  in  most  soils,  and  is  freely 
used  by  plants  of  high  protein  content  as  well  as  by  such 
crops  as  cabbage,  kohlrabi,  turnips,  rutabagas,  onions,  gar- 
lic, and  horse-radish.  Common  salt,  NaCl,  has  sometimes 
been  used  as  a  manure,  but  it  is  not  supposed  to  furnish 
necessary  plant  food,  and  while  it  has  given  beneficial  results 
at  times,  often  it  has  failed  to  do  so. 

Mixed  fertilizers  are  very  common  on  the  market.     The 
fertilizer  manufacturer  very  generally  does  the  mixing  of  the 


224  CHEMISTRY  AND   DAILY  LIFE 

basal  materials  already  described,  and  sells  them  to  the 
farmer  as  complete  fertilizers.  Mixed  fertilizers  are  indis- 
criminately recommended  for  general  use  and  all  sorts  of 
startling  claims  are  made  for  them  by  the  manufacturers. 
They  are  offered  as  universal  fertilizers,  irrespective  of  the 
plant  food  contained  in  the  given  soil  or  the  needs  of  the 
crop  to  be  grown.  The  "  corn  special  "  of  one  manufacturer 
may  be  like  the  "  tobacco  special  "  of  another  firm.  The 
farmer  must  study  the  real  needs  of  his  fields,  and  when  he  has 
done  this,  he  will  prefer  to  buy  the  basal  fertilizing  materials 
of  definite  and  known  composition  and  apply  the  proportion 
that  is  best  adapted  to  his  needs,  rather  than  buy  mixed  goods. 
It  is  wise  to  practice  home  mixing.  The  difference  in  the 
cost  of  complete  fertilizers  and  the  basal  materials  per  pound 
of  plant  food  is  considerable.  It  has  been  estimated  to  be 
from  eight  to  ten  dollars  per  ton.  On  the  farms  of  the 
eastern  United  States  it  is  becoming  common  practice  to  buy 
the  basal  materials  and  mix  them  at  home. 

The  proper  selection  of  commercial  fertilizers  is  obviously 
of  great  importance.  It  is  impossible  to  give  definite  direc- 
tions as  to  kinds  and  quantities  of  fertilizers  for  different  crops, 
because  soils  differ  greatly  in  their  content  of  plant  food.  But 
by  carefully  noting  the  growing  crop,  some  valuable  sugges- 
tions may  be  gained  as  to  which  fertilizers  are  most  needed. 
So  a  crop  with  a  deep  green  color,  well-developed  leaf,  and 
luxuriant  growth  is  not  suffering  from  a  lack  of  nitrogen  or 
potassium.  A  rank  excessive  growth  of  leaf  and  stem,  but 
imperfect  bud  and  flower  development,  and  small  under- 
sized grain,  denotes  plenty  of  nitrogen  and  potassium,  but  a 
lack  of  phosphorus,  These  suggestions  are  helps,  but  it  is 
not  always  safe  to  depend  upon  them  entirely.  Field  ex- 
periments are  necessary.  To  determine  with  any  degree  of 
certainty  what  particular  fertilizer  would  be  helpful,  the 


COMMERCIAL   FERTILIZERS 


225 


farmer  must  conduct  some  experiments  himself.  This  can  be 
done  by  carefully  marking  off  certain  portions  of  the  field  of 
uniform  soil  into  plots  of  definite  size,  and  then  using  dif- 
ferent fertilizing  materials  on  these  plots.  A  plot  one  rod 
wide  and  eight  rods  long  contains  one-twentieth  of  an  acre, 
and  is  of  convenient  size  for  experiment.  Careful  notes 
should  be  kept  during  the  growing  season,  and  the  weights 
of  the  harvested  crops  should  be  recorded.  This  gives  defi- 
nite information,  especially  if  continued  over  several  years. 
When  it  has  thus  been  established  what  basal  materials  are 
most  effective,  then  the  cheapest  sources  of  these  materials 
should  be  selected.  The  diagram  given  below  indicates  the 
arrangement  of  the  plots  and  the  amounts  of  materials  to 
apply.  In  addition  to  the  fertilizer,  a  part  of  the  plots  may 
be  limed.  This  will  give  evidence  as  to  the  need  of  correct- 
ing the  acidity  of  the  soil. 

DIAGRAM 


Plot  1.  None. 

Plot  2.  N (Dried  Blood,  30  lb.). 

Plot  3.  P  (Steamed  Bone  Meal, 

10  lb.). 
Plot  4.  S  (Gypsum,  10  lb.). 

Plot  5.   K  (Muriate  of  Potash, 

10  lb.). 
Plot  6.  None. 

Plot  7.  N  and  P  (Blood  and  Bone) . 


Plot  8.  N  and  S  (Blood  and  Sul- 
phate). 

Plot  9.  P  and  S  (Bone  and  Sul- 
phate). 

Plot  10.  P  and  K  (Bone  and 
Chloride). 

Plot  11.  N,  P,  and  S  (Blood, 
Bone,  and  Sulphate). 

Plot  12.  N,  P,  S,  and  K  (Blood, 
Bone,  Sulphate,  and 
Chloride). 

Plot  13.  None. 


No  definite  rule  can  be  given  as  to  the  amount  of  ferti- 
lizer to  apply,  for  soils  vary  in  their  original  content  of  plant 


Q 


226 


CHEMISTRY  AND   DAILY  LIFE 


food ;  and  then  the  kind  of  crop  to  be  grown  is  also  a  factor. 

Five  hundred  pounds  per  acre  on  soils  already  fertile  is  a  heavy 

application  for  ordinary 
farm  crops  and  will  only 
give  profitable  returns  on 
fertile  soils  when  used  in 
intensive  farming.  It  is 
better  to  make  lighter  ap- 
plications of  from  100  to 
200  pounds  of  any  one 
basal  material  per  acre, 
and  to  vary  the  amount 
from  year  to  year,  when 
experience  has  shown 
that  economical  returns 
can  be  expected  from 
heavier  applications* 

To  protect  the  farmer 
against  fraud,  many  state 
fertilizer  laws  require 
that  the  guaranteed  anal- 
ysis or  formula  of  a  fer- 


,itw 


FIG.  80. — A  bag  for  commercial  fertilizer 
with  the  analysis  printed  on  it. 


tilizer  should  be  placed 
on  the  bag  containing  it. 
Most  of  such  legends  are 

so  complicated  as  to  confuse  and  are  of  no  more  value 
than  so  many  Greek  letters.  A  sample  of  such  a  label  is 
given  on  page  227. 

The  things  that  are  essential  in  the  statement  on  page  227  are 
the  amounts  of  "nitrogen,"  "  available  phosphoric  acid,"  and 
"  potash."  The  rest  is  superfluous  and  only  confusing.  The 
label  means  that  there  is  contained  in  this  fertilizer  8  to  10 
per  cent  of  available  P2O5 ;  but  this  is  erroneously  called 


COMMERCIAL  FERTILIZERS  227 


GENERAL  CROP  BRAND 

GUARANTEED    ANALYSIS 


PER  CENT 

Nitrogen                       

0.82  — 
1.0   - 
8.0   - 
17.0  - 
10.0   - 
11.0  - 
6.0   - 

1.65 
2.0 
10.0 
21.0 
12.0 
13.0 
7.0 

Ammonia 

Available  phos  acid     

Equal  bone  phos 

Total  phos.  acid  

Potash  sulphate  . 

Potash       

phosphoric  acid  (see  Chapter  VII).  It  would  be  better  if 
the  label  stated  the  real  fact,  which  is  that  the  fertilizer  con- 
tains 3.4  to  4.4  per  cent  of  available  phosphorus,  P,  for  this  is 
the  equivalent  of  the  statement  "8  to  10  per  cent  available 
phosphoric  acid."  Furthermore,  potassium  is  expressed 
on  the  label  as  potash,  meaning  K2O.  The  6  to  7  per  cent 
of  potash  are,  however,  equivalent  to  4.9  to  5.8  per  cent  of 
potassium.  In  expressing  the  analysis  of  fertilizers,  the  per- 
centages of  the  elements '  nitrogen,  phosphorus,  and  potassium 
ought  to  be  given,  because  these  represent  the  things  of  actual 
worth.  This  simple  and  intelligible  system  of  expressing 
the  results  of  a  fertilizer  analysis  is  known  as  the  elementary 
system,  and  it  ought  to  be  adopted  universally. 

QUESTIONS 

1.  What  is  a  commercial  fertilizer,  and  what  elements  are  the 
main  ones  supplied  in  a  complete  fertilizer  ? 

2.  Name  two  kinds* of  nitrogenous  fertilizers.     How  much   ni- 
trogen would  there  be  in  200  pounds  of  Chili  saltpeter?     In  100 
pounds  of  ammonium  sulphate  ?     How  do  these  amounts  compare 
with  the  requirements  of  100  bushels  of  corn  ? 


228  CHEMISTRY  AND   DAILY  LIFE 

3.  When  should  nitrate  of  soda  be  applied  to  the  soil  ? 

4.  What  is  the  objection  to  the  use  of  scrap  leather  as  a  source 
of  nitrogen  for  fertilizers  ? 

5.  Name  three  kinds  of  phosphate  fertilizers.     How  does  an 
acid  phosphate  differ  from  floats  ? 

6.  What  does  basic  slag  come  from  ?    On  what  kind  of  soils  is  it 
doubly  useful  ? 

7.  Where  do  potash  salts  mainly  come  from  ?    What  compounds 
of  value  are  contained  in  wood  ashes  ? 

8.  In  what  form  is  it  best  to  add  lime  to  a  soil,  and  why  should 
it  be  added  ?     Of  what  use  is  gypsum  when  added  to  soils  ? 

9.  How  are  fertilizers  commonly  sold  ?    What  is  meant  by  home 
mixing  ? 

10.  How  can  the  fertilizer  requirements  of  a  soil  be  best  deter- 
mined ? 

11.  A  mixed  fertilizer  contains  2  per  cent  of  nitrogen,  2  per  cent 
of  phosphorus,  and  8  per  cent  of  potassium.    How  many  pounds  of 
ammonium  sulphate,  bone  meal,  and  kainite  would  be  needed  to 
make  up  a  ton  of  such  a  mixture  ? 


CHAPTER   XVI 

FARM  MANURE 

OF  all  fertilizers,  farm  manure  is  the  oldest  and  still  the 
most  popular.  It  consists  of  the  liquid  and  solid  excreta  of 
the  farm  stock,  plus  the  bedding  employed.  Early  Roman 
writers  called  attention  to  the  fact  that  the  application  of 
the  excreta  of  farm  animals  resulted  in  increased  crop  pro- 
duction, and  from  that  time  to  the  present  day  the  majority 
of  farmers  have  placed  their  reliance  on  such  manures  for 
maintaining  the  fertility  of  the  land. 

A  well-kept  manure  heap  may  safely  be  taken  as  one  of  the 
surest  indications  of  thrift  and  success  in  farming.  The  fer- 
tilizer value  of  the  manure  produced  each  year  by  the  dif- 
ferent classes  of  farm  animals  in  the  United  States  aggre- 
gates a  total  of  $2,225,700,000.  This  estimation  is  based  on 
the  value  usually  given  to  phosphorus  (P),  potassium  (K), 
and  nitrogen  (N)  in  commercial  fertilizers,  which  are  re- 
spectively 10  cents,  6  cents,  and  15  cents  per  pound  for  the 
materials  in  the  order  named.  It  is  safe  to  say  that  the  manure 
made  on  the  farms  of  Wisconsin  has  a  value  of  $75,000,000  per 
year,  and  that  through  improper  handling  one-third  of  the  value 
is  lost. 

The  manure  produced  by  the  various  classes  of  farm  ani- 
mals differs  greatly  in  its  composition  and  physical  proper- 
ties. The  manure  from  the  pig  and  cow  (including  both  the 
solid  and  liquid  excrement)  is  very  high  in  water,  containing 
at  least  75  per  cent.  Because  it  is  so  moist,  it  ferments  very 
slowly  when  piled,  and  so  it  has  been  called  a  cold  manure. 

229 


230  CHEMISTRY  AND   DAILY  LIFE 

On  the  other  hand,  the  combined  excreta  from  the  horse  and 
sheep  have  a  lower  water  content,  about  65  to  70  per  cent. 
These  ferment  more  rapidly  and  are  called  hot  manures. 
While  the  composition  of  manure  varies  greatly,  a  ton  of 
mixed  manure  of  average  composition  generally  contains  ap- 
proximately 2  pounds  of  phosphorus  (P),  10  pounds  of 
nitrogen  (N),  and  8  pounds  of  potassium  (K). 

The  composition  and  value  of  manure  is  influenced  by  three 
things  :  (1)  the  nature  of  the  ration  fed  the  animal;  (2)  the  kind 
and  age  of  the  animal ;  (3)  the  kind  and  amount  of  the  bedding 
used.  The  manure  from  animals  that  are  fed  on  rich  foods, 
like  clover,  alfalfa,  bran,  and  cottonseed  meal  is  better  than 
that  from  animals  fed  on  timothy  hay,  straw,  corn  stover, 
and  other  feeds  not  rich  in  nitrogen  and  phosphorus,  and  to 
which  little  or  no  grain  has  been  added.  Furthermore,  the 
manure  from  young 'and  growing  animals,  as  calves  and  colts, 
is  not  so  valuable  as  that  from  older  animals,  and  especially 
animals  that  are  fattening.  Young  growing  animals  use  up 
more  of  the  nitrogen,  phosphorus,  and  potassium  in  the  food  for 
their  own  bodies  to  make  blood,  bone,  and  flesh  than  do  older 
animals.  Mature  animals  that  are  poor  in  flesh,  but  are  fat- 
tening, produce  a  rich  manure,  for  the  production  of  fat  does 
not  require  the  retention  of  nitrogen,  phosphorus,  and  potassium, 
as  does  the  building  of  bone  and  muscle.  A  milch  cow  will 
not  produce  as  rich  manure  as  a  fattening  steer  on  the  same 
ration.  This  is  because  some  of  the  fertilizer  constituents 
go  over  into  the  milk  and  so  are  not  returned  in  the  excreta. 
There  is  in  5000  pounds  of  milk  fertilizing  material  equal  in 
value  to  about  $4-90-  If  the  milk  is  sold,  this  is  lost  to  the 
farm.  If  the  milk  is  skimmed  and  the  butter  is  sold,  prac- 
tically no  loss  occurs,  for  the  nitrogen,  potassium,  and  phos- 
phorus are  in  the  skimmed  milk.  The  fertilizer  value  of  500 
pounds  of  butter  is  only  about  10  cents.  This  shows  how 


FARM  MANURE  231 

a  dairy  or  animal  farm  has  the  advantage  over  a  grain  farm  in 
helping  to  keep  up  the  fertility  on  the  land.  The  bedding  em- 
ployed will  alter  the  composition  of  the  final  manure.  The 
richer  the  bedding,  the  richer  the  manure;  but  the  materials 
commonly  used,  such  as  the  straws  and  sawdust,  are  low  in 
fertilizer  ingredients.  If  peat  is  used,  it  will  increase  the 
nitrogen  content  of  the  manure  considerably. 

The  great  value  of  farm  manure  is  not  appreciated  to  its  full- 
est extent.  A  large  proportion  of  our  farmers  seem  to  have 
little  realization  of  the  immense  loss  incurred  through  the  waste 
of  this  important  product  of  the  farm.  They  begrudge  the 
time  and  labor  required  to  remove  it  from  the  farm  and  feed- 
ing lot,  and  it  is  not  uncommon  to  see  the  purchase  of  com- 
mercial fertilizers  and  the  waste  of  farm  manure  going  on  at 
the  same  time  and  on  the  same  farm.  Barns  are  often  built 
on  steep  hillsides  or  the  banks  of  running  streams,  which 
practice  insures  a  large  waste.  The  value  of  manure  may 
be  increased  in  two  ways:  (I)  by  the  selection  and  use  of  feeds 
that  are  rich  in  fertilizing  materials,  or  (2)  by  purchasing 
suitable  commercial  plant  food  and  adding  it  to  the  manure. 
The  first  method  means  that  the  farmer  must  purchase  some 
of  the  mill  by-products  now  offered  for  sale,  and  feed  them 
to  his  stock.  A  successful  stock  man  usually  finds  it  profit- 
able to  thus  reenforce  his  home-grown  grains  with  one  or  more 
of  the  various  mill  by-products.  A  farmer  who  is  buying 
large  amounts  of  concentrates  is  increasing  the  fertility  of  his 
land,  provided  he  is  saving  the  manure.  Bran  is  a  concen- 
trate that  is  rich  in  phosphorus  and  potassium,  while  oil 
meal  and  gluten  feed  are  rich  in  nitrogen. 

The  second  method  of  enhancing  the  value  of  manure  is 
practiced  in  systems  of  animal  husbandry  as  well  as  in  sys- 
tems of  mixed  farming.  Experiments  have  shown  that  on 
certain  soils,  reenforcement  of  the  manure  with  either  kainite, 


232  CHEMISTRY  AND   DAILY  LIFE 

gypsum,  floats,  or  acid  phosphate  results  in  profitable  in- 
crease in  crops.  The  greatest  profit,  however,  comes  from  the 
use  of  either  acid  phosphate  or  floats.  Any  of  these  materials 
can  be  applied  at  the  rate  of  40  pounds  per  ton  of  manure. 
To  secure  the  greatest  profit,  the  manures  for  most  soils  should 
probably  be  reenforced  with  floats  and  gypsum,  for  these  ma- 
terials furnish  additional  phosphorus  and  sulphur  respec- 
tively, of  which  elements  there  is  often  a  lack. 

Farm  manure  is  a  perishable  product  and  must  be  handled 
with  intelligence  to  obtain  the  greatest  value  from  it.  Doubt- 
less, as  manure  is  handled  on  most  farms,  only  about  one- 
half  of  its  worth  is  realized.  The  greatest  loss  is  through 
the  waste  of  the  liquid  excrement  by  not  using  sufficient  bed- 
ding to  absorb  it.  The  boring  of  holes  in  the  floor  for  the 
express  purpose  of  allowing  the  urine  to  run  off  as  rapidly  as 
possible  is  by  no  means  an  uncommon  practice.  Pound  for 
pound  the  liquid  excrement  is  more  valuable  than  the  solid.  It 
contains  more  than  one-half  of  the  nitrogen,  most  of  the  potas- 
sium, and  but  a  trace  of  the  phosphorus  excreted  by  the  ani- 
mal. Most  of  the  phosphorus  is  found  in  the  solid  droppings. 
Another  fact  of  great  importance  in  this  connection  is  that 
the  plant  food  in  the  urine  is  soluble  in  water  and  conse- 
quently more  available  to  plants  than  that  in  the  solid  dung. 
The  solid  excrement  consists  in  part  of  the  indigestible  por- 
tions of  the  food,  and  before  its  nitrogen  can  become  avail- 
able to  plants,  it  must  undergo  decomposition  and  decay. 
Besides  the  losses  due  to  incomplete  absorption  of  the  urine 
by  the  bedding,  manure  suffers  heavily  from  leaching  by  rains. 
Often  animals  are  confined  in  yards  and  no  effort  at  all  is 
made  to  save  the  droppings,  and  the  result  is  that  the  rains 
wash  them  away.  Very  often  when  stables  are  cleaned  out, 
the  manure  is  thrown  under  the  eaves  of  the  barn  or  shed 
and  the  rain  from  the  roof  soon  saturates  the  pile  and  a  dark 


FARM  MANURE 


233 


liquid  begins  to  run  away.  This  contains  much  plant  food, 
and  it  is  usually  lost  by  draining  into  a  stream  or  soaking 
into  the  ground  where  no  plants  are  to  grow.  Then  again,  it 
often  happens  that  manure  is  thrown  into  large  piles  that 
are  allowed  to  lie  exposed  to  the  rain  and  weather  for  months. 
Under  such  conditions  it  gets  "  warm "  and  ferments. 


FIG.  81.  — An  only  too  common  way  of  wasting  farm  manure. 

This  fermentation  is  caused  by  bacteria,  and  results  in  the 
production  of  ammonia  (NH8),  which  contains  nitrogen. 
The  ammonia  gas  escapes  into  the  air  and  is  lost.  Many  a 
boy  on  the  farm  has  suffered  with  smarting  eyes  when  re- 
moving the  accumulated  .manure  from  the  horse  stable. 
Leaching  and  fermenting  cause  great  losses  to  manure,  which 
can  largely  be  prevented.  Thus  if  the  manure  pile  be  made  so 
compact  that  the  air  cannot  penetrate  it,  the  most  destruc- 
tive bacteria  cannot  live  in  it  and  hence  hot  fermentation  is 
prevented.  Other  bacteria  will  be  active  in  the  pile  and  cause 


234  CHEMISTRY  AND   DAILY  LIFE 

rotting ;  but  this  is  not  harmful,  being  on  the  contrary  a  pro- 
cess greatly  desired  in  the  production  of  manure  for  market 
gardening.  The  secret  of  keeping  the  hot  fermentation  down 
is  to  keep  the  manure  heap  compact  and  moist.  This  allows  the 
pile  to  rot,  but  the  loss  of  nitrogen  as  ammonia  will  be  small. 

It  is  better  to  allow  the  manure  to  accumulate  in  the  stable 
and  be  trampled  underfoot  by  the  animals,  providing  plenty 
of  bedding  is  used,  than  to  throw  it  out  in  a  pile  to  ferment 
and  leach.  The  tramping  in  the  stable  keeps  the  manure 
solid  and  moist,  and  checks  the  heating.  This,  however,  is 
not  a  sanitary  way,  especially  for  dairy  cows.  But  in  some 
cases,  for  instance,  where  calves,  colts,  sheep,  or  steers  are 
fed  loose  in  a  stable,  the  manure  might  be  allowed  to  collect 
the  entire  winter.  As  soon  as  the  animals  are  taken  out,  the 
manure  should  be  hauled  to  the  field  and  spread.  In  general, 
it  is  better  to  clean  the  stables  out  daily  and  haul  the  manure 
directly  to  the  field.  This  is  the  very  best  practice  wherever 
possible,  and  saves  the  manure  more  perfectly  than  any  other 
method.  Sometimes  the  ground  is  too  wet  or  the  fields,  too 
hilly,  or  other  causes  arise  which  prevent  hauling,  and  make 
it  necessary  to  store  the  manure.  In  such  cases,  a  good  com- 
pact pile  should  be  built  where  water  can  be  applied  to  keep 
it  from  getting  hot.  The  pile  should  be  made  solid  and  so 
deep  that  the  hardest  rain  will  not  soak  through.  This  can 
be  accomplished  by  making  the  piles  from  five  to  six  feet  high. 
A  basin-like  depression  with  the  bottom  and  sides  of  cement 
is  a  good  place  to  store  manure.  A  roof  is  not  so  necessary. 
When  manure  is  exposed  in  loose  shallow  piles,  the  losses  of 
plant  food  in  a  few  months  may  be  at  least  one-half  of  the  total 
in  the  manure. 

It  has  already  been  said  that  manure  should  be  hauled  to 
the  field  as  soon  as  possible.  It  should  also  be  spread  at  once. 
It  is  very  wasteful  of  both  fertilizer  and  labor  to  dump 


FARM  MANURE  235 

manure  in  piles  and  let  it  lie  there  for  weeks  before  spreading 
it.  Every  rain  will  wash  out  some  soluble  material  into  the 
soil  just  around  the  pile.  This  will  give  a  spotted  meadow 
or  grain  field  the  next  season.  The  plants  growing  where  the 
piles  stood  will  grow  more  luxuriantly  and  mature  later  than 
the  rest  of  the  field.  Spreading  with  the  manure  spreader 
is  a  good  way  to  distribute  the  manure.  On  heavy  soils 


FIG.  82.  — A  manure  spreader  in  action. 

containing  much  clay  more  benefit  will  be  derived  from  fresh 
manure  than  from  those  that  are  well  rotted.  Fresh  manure 
warms  these  cold  soils  and  makes  them  more  porous.  On 
light  sandy  soils,  on  the  other  hand,  manures  that  are  well 
rotted  will  be  most  beneficial.  Fresh  manure  has  a  forcing 
effect  and  tends  to  produce  stems  and  leaves  at  the  expense 
of  fruit  and  grain.  It  is,  therefore,  better  for  early  garden 
truck,  grasses,  and  foliage  plants  than  for  cereals.  The  latter 
may  lodge  easily  if  grown  directly  after  manuring.  Corn  is 
usually  benefited  by  liberal  applications  of  fresh  manure. 
In  fact,  when  in  doubt  as  to  where  to  apply  the  manure,  "  use 
it  on  corn."  It  is  better  to  apply  small  quantities  of  manure 
to  the  land  often  rather  than  large  quantities  not  so  often.  Ten 
to  fifteen  tons  per  acre,  once  in  three  years,  of  manure  of 


236  CHEMISTRY  AND   DAILY  LIFE 

average  composition  will  replace  the  plant  food  removed  by 
the  average  crops.  This  is  not  considered  a  heavy  applica- 
tion. With  a  manure  spreader  a  small  quantity  of  manure 
can  be  made  to  cover  a  large  area  of  ground,  and  thus,  if  desired, 
the  fields  can  be  treated  oftener  with  smaller  amounts. 

By  green  manuring  is  meant  the  plowing  under  of  green 
plants  so  that  in  their  decay  in  the  soil  they  will  add  humus 
and  produce  carbon  dioxide.  The  addition  of  humus  aids 
the  soil  in  retaining  moisture,  and  at  the  same  time  puts 
it  in  better  physical  condition  for  cultivation;  thus  sandy 
soils  retain  water  better  and  clays  become  warmer  and  more 
workable.  Any  kind  of  plant  can  be  used  for  a  green  manur- 
ing crop.  It  is  better  to  plow  under  weeds  while  they  are  green 
than  to  let  them  go  to  seed.  Rye  is  a  common  green  manuring 
crop.  It  is  sown  in  the  autumn  and  plowed  under  in  the 
spring.  The  best  green  manuring  plants  are  the  legumes, 
because  they  add  nitrogen,  and  this  is  what  most  soils  need. 
Clovers,  soy  beans,  vetches,  and  cowpeas  are  all  good.  Red 
clover  is  the  most  common  one  used.  These  plants  produce 
good  results  even  when  the  crop  is  harvested,  and  only  the 
stubble  turned  under.  But  because  of  the  large  root  systems 
of  alfalfa  and  red  clover,  their  stubble  leaves  much  more 
nitrogen  than  the  roots  of  the  pea  or  bean.  No  plant  but 
the  legume  adds  nitrogen  to  the  soil.  All  others  can  give  back 
to  the  soil  only  the  nitrogen  which  they  obtained  from  it  in  the 
first  place.  Usually  it  is  better,  in  systems  of  animal  hus- 
bandry farming,  to  cut  the  clover  for  hay  and  return  the 
manure  to  the  land.  In  this  way  the  farmer  gets  the  benefit 
of  the  feed  and  nearly  all  the  plant  food  goes  back  to  the 
land,  provided  he  saves  the  manure. 


• 

FARM  MANURE  237 

QUESTIONS 

1.  What  is  the  value  of  the  manure  annually  produced  in  your 
state  and  how  does  it  compare  with  the  value  of  the  dairy  products  ? 

2.  What  is  a  cold  manure  ?     What  is  its  approximate  water 
content  ? 

3.  How  many  pounds  of  nitrogen  and  phosphorus  are  there  re- 
spectively in  a  ton  of  manure  ? 

4.  What  factors  influence  the  composition  of  manure  ? 

5.  Name  two  methods  of  increasing  the  value  of  manure. 

6.  How  is  the  value  of  manure  lost  ? 

7.  How  would  you  prevent  harmful  fermentation  ? 

8.  How  would  you  prevent  leaching  ? 

9.  What  is  the  best  way  to  apply  manure,  and  how  many  tons 
per  acre  should  be  applied  annually  ? 

10.   What  is  meant  by  green  manuring,  and  of  what  benefit  is  it  ? 


CHAPTER  XVII 
PLANT   LIFE   AND    WHAT   IT   PRODUCES 

THE  farmer  rears  plants  and  animals.  He  grows  the  plants 
on  his  land  and  his  animals  feed  on  the  plants.  He  sells  a 
part  of  his  produce  to  those  who  need  it  and  thus  secures  the 
means  to  buy  clothing  and  tools  for  farming  purposes,  and 
to  provide  for  the  education  of  his  children.  He  begins  his 
work  with  the  seeds  of  plants. 

All  living  things  possess  certain  properties  in  common. 
Careful  study  has  shown  that  the  living  substance  in  plants 
and  animals  is  practically  the  same.  This  living  substance  is 
called  protoplasm.  It  is  a  clear,  granular  substance  of  about 
the  consistency  of  the  white  of  egg.  It  is  this  that  grows, 
builds  the  plant  and  the  animal,  and  performs  all  the  func- 
tions of  life.  Exactly  what  it  is,  is  not  known,  but  it  is  closely 
allied  to  some  of  the  complex  bodies  which  the  plant  can  build, 
as,  for  example,  the  proteins.  Protoplasm  is  found  in  every 
plant  and  animal,  not  in  one  large  mass,  but  in  thousands  of 
little  parts  called  cells.  These  are  so  small  that  the  compound 
microscope  must  be  used  in  order  to  see  them.  The  walls 
of  different  cells  vary  in  thickness.  They  separate  the  cells 
from  one  another  and  enable  them  to  maintain  their  form. 
In  most  of  the  common  animals  some  of  the  cells  have  thick 
walls  that  are  filled  with  mineral  matter.  These  make  up 
the  skeleton,  while  the  rest  of  the  cells  are  soft-walled.  In 
plants  most  of  the  cells  have  fairly  firm  walls.  As  long  as  the 
protoplasm  is  alive  it  is  at  work.  One  of  its  peculiar  func- 
tions is  to  manufacture  new  protoplasm  out  of  various  sub- 

238 


PLANT  LIFE  AND  WHAT  IT  PRODUCES       239 

stances  which  are  not  of  themselves  alive.  The  new  pro- 
toplasm thus  formed  is  alive  and  like  that  which  produced 
it.  A  plant  or  animal  which  is  increasing  in  size  and  weight 
is  making  new  protoplasm.  Among  the  other  activities  of 
protoplasm  are  the  absorption  and  assimilation  of  food  and 
the  storing  of  reserve  foodstuffs  in  the  seed  for  future  use, 
also  the  building  of  new  cell  walls,  the  secreting  of  substances 
for  protection  and  the  repair  of  injuries  that  may  have  been 
received,  and  the  elimination  of  various  waste  products  that 
are  constantly  being  formed. 

A  knowledge  of  the  seed  and  seed  germination  is  of  funda- 
mental importance.     On  examining  a  kernel  of  corn  it  will 


FIG.  83.  — A  good  ear  of  corn.     The  kernels  are  of  good  shape. 

be  seen  that  it  contains  a  store  of  food  material  that  is  intended 
to  nourish  the  young  plant  till  it  has  sufficiently  developed  so 
that  it  can  draw  sustenance  from  the  soil  and  the  air.  It  is  to 


240  CHEMISTRY  AND  DAILY  LIFE 

be  borne  in  mind  that  plants  live  to  produce  seed,  which  will 
in  turn  reproduce  their  kind.  If  a  kernel  of  corn  is  soaked  in 
water  overnight,  it  can  easily  be  separated  into  its  distinct 
parts.  There  is  the  tough  outer  coating  of  the  seed ;  at  the 
tip  is  the  cream-colored  germ ;  packed  around  the  germ  is 
a  layer  of  food  material,  mainly  starch ;  and  outside  of  this 
there  is  a  still  harder  layer  made  up  of  starch  and  protein. 
The  germ  is  the  only  part  of  the  seed  that  sprouts.  It  may,  in- 
deed, be  called  the  baby  plant.  It  is  the  living  protoplasm 
of  the  seed.  The  other  materials  are  placed  near  the  germ 
for  the  sole  purpose  of  supplying  it  with  food  when  it  first 
begins  to  grow.  Every  seed  that  is  to  germinate  must  have  this 
living  germ,  this  embryonic  plant,  in  it ;  but  the  seed  must  also 
be  supplied  with  moisture,  warmth,  and  air.  Dry  seeds  do 
not  germinate.  In  fact,  the  way  to  prevent  seeds  from  growing 
is  to  keep  them  dry.  This  is  well  known  from  common  ex- 
perience. On  the  other  hand,  wet  seeds  will  either  grow  or 
rot.  They  will  grow  if  the  germ  is  in  good  condition  and 
warmth  and  air  are  furnished.  Who  has  not  seen  the  seed 
start  in  the  shock  or  stack  during  a  wet  season,  and  who  has 
not  noticed  that  the  beans  rot  when  planted  too  early  in 
moist,  cold  ground? 

After  the  seed  has  been  planted  in  sufficiently  warm,  moist 
ground,  it  absorbs  moisture  and  swells.  The  seed  coat  is 
broken  open,  and  the  germ  sends  a  root  which  starts  down- 
ward into  the  soil.  A  little  later  a  tiny  shoot  is  put  forth, 
which  grows  upward  to  form  the  stem,  that  is,  the  part  of 
the  plant  above  the  ground.  During  this  early  period  of 
growth  the  germ  was  fed  by  the  starch  and  protein  that 
surrounded  it  in  the  seed.  That  the  ground  must  be  suffi- 
ciently warm  in  order  that  seeds  may  sprout  and  grow  is  a  matter 
of  common  experience.  So  oats  sown  during  cold  weather 
have  sometimes  remained  unsprouted  for  a  month,  while- 


PLANT  LIFE  AND  WHAT  IT  PRODUCES        241 

when  sown  in  warm  weather  they  came  up  in  about  one- 
third  of  that  time.  Seeds  of  different  plants  require  different 
temperatures  to  awake  them  and  make  them  sprout,  that  is, 
germinate.  Thus  seeds  of  wheat,  oats,  rye,  and  barley 
germinate  when  the  ground  is  still  quite  cool,  and  so  the 


FIG.  84.  —  Germinating  6orn  kernels. 

farmer  sows  them  in  early  spring.  Corn  requires  warmer 
ground  than  wheat ;  and  for  seeds  of  cotton,  cowpeas,  or 
cucumbers  the  ground  must  be  still  warmer.  A  good  farmer 
never  plants  these  seeds  until  the  soil  has  warmed  up. 

It  has  already  been  stated  in  Chapter  XIV  that  the  air 
must  have  access  to  the  roots  of  growing  plants.  Sprouting  seeds 
also  need  air.  So  if  corn  is  planted  in  a  field  which  is  then 
overflowed  with  water,  it  will  not  come  up.  There  are,  indeed, 
some  seeds  that  will  germinate  under  water,  like  the  seeds 
of  rice  and  water  lilies ;  but  even  in  such  cases,  there  must 
be  oxygen  dissolved  in  the  water.  Packing  the  soil  too 


242  CHEMISTRY  AND  DAILY  LIFE 

closely  around  the  seed  will  keep  out  the  air  and  so  hinder  or 
prevent  germination.  This  is  particularly  true  of  heavy  clay 
soils.  On  the  other  hand,  packing  loamy  or  sandy  soils 
around  seeds  aids  germination  by  bringing  the  seeds  in  con- 
tact with  water  films  surrounding  the  soil  grains.  These 
soils,  being  more  porous,  still  permit  sufficient  access  of  air 
to  the  seed.  Some  plants  experience  more  difficulties  than 
others  in  their  efforts  to  come  up,  that  is,  to  reach  the  surface 
of  the  ground.  For  example,  instead  of  sending  up  slender 
stems  like  the  peas,  or  thin  blades  like  the  barley,  they  raise 
the  entire  swollen  seed  out  of  the  soil,  and  try  to  lift  a  portion 
of  the  ground  up  with  it.  The  bean  is  a  plant  of  this  kind. 
In  planting  seeds  these  two  types  of  behavior  must  be  kept  in 
mind.  Thus  wheat,  barley,  peas,  and  corn  belong  to  the  first 
type;  and  they  may  therefore  always  be  planted  a  little 
deeper  than  beans,  radishes,  beets,  carrots,  melons,  clover, 
buckwheat,  and  squash,  which  are  of  the  second  type.  The 
latter  should  never  be  covered  more  than  five  times  their 
thickness.  Other  seeds  may  be  covered  somewhat  deeper, 
but  no  seed  should  be  planted  deeper  than  necessary  to  insure 
a  proper  supply  of  soil  moisture. 

After  the  tiny  root  has  started  to  grow  from  the  seed,  it 
becomes  clothed  with  a  downy  fringe  that  looks  like  the 
finest  silk.  These  delicate  fibers  are  called  root  hairs.  They 
absorb  water  and  nutrients  from  the  soil  for  the  further 
growth  of  the  plant.  During  the  life  of  a  plant  the  root  and 
stem  that  started  in  the  seed  normally  continue  to  grow  by 
division  of  certain  groups  of  cells  near  their  tips.  After  a 
young  plant  has  used  up  the  material  of  the  seed,  it  must 
gather  its  own  food  supply.  A  part  of  this,  namely,  the 
carbon,  is  taken  from  the  air  by  means  of  the  leaf,  but  water 
and  all  of  the  other  things  necessary  for  growth  are  taken  from 
the  soil  through  the  root,  which  is  consequently  a  very  impor- 


PLANT  LIFE  AND  WHAT  IT  PRODUCES        243 


tant  organ.  It  not  only  holds 
the  plant  firmly  in  position,  but 
it  also  performs  the  very  im- 
portant functions  of  absorbing 
water,  nitrates,  phosphates,  and 
various  other  necessary  mineral 
nutrients.  All  of  these  must  be 
in  solution  in  the  soil  water  in 
order  that  they  may  be  absorbed, 
for  no  solid  matter  can  enter  a 
plant.  The  living  membrane 
that  lines  the  inside  of  each  cell 
wall  of  a  root  hair  will  not  let 
the  finest  solid  particles  pass, 
not  even  if  they  are  finer  than 
flour.  No  part  of  the  soil  can 
act  as  plant  food  unless  it  is 
first  dissolved.  Just  as  sugar 
and  salt  dissolve  in  water,  so 
certain  substances  like  the  ni- 
trates, phosphates,  silicates,  sul- 
phates, chlorides,  carbonates, 
etc.,  in  the  soil  pass  into  solu- 
tion in  the  soil  water.  In  ordi- 
nary soil  the  amount  of  material 
dissolved  in  the  soil  water  is  quite 
slight,  that  is  to  say,  soil  waters 
are  generally  quite  dilute  solu- 
tions. Indeed,  it  would  take 
several  thousand  pounds  of  soil 
water  to  carry  to  the  plant  one 
pound  of  calcium,  phosphorus, 
or  any  other  single  element 


FIG.  85.  —  Root  hairs.  On  the 
right  the  soil  has  not  been 
washed  away. 


244  CHEMISTRY  AND   DAILY  LIFE 

essential  for  vegetable  life.  It  is  this  soil  water,  then,  with 
its  plant  food  in  solution  that  is  absorbed  by  the  root  hairs  on 
the  roots  and  thus  gains  its  way  into  the  plant.  To  accomplish 
their  work,  the  root  hairs  penetrate  between  and  wind  around 
the  soil  particles,  lying  in  the  film  of  water  that  surrounds 
the  solid  grains  of  the  soil.  Moreover,  as  already  mentioned 
in  Chapter  XIV,  these  rootlets,  as  they  grow,  continually  give 
off  carbon  dioxide.  This  is  absorbed  by  the  soil  water,  which 
thus  becomes  a  better  solvent  for  many  of  the  ingredients 
of  the  soil. 

The  sap  passes  upward  from  the  root  to  the  leaf  as  a  result 
of  the  action  of  capillarity  and  evaporation  of  water  from  the 
surface  of  the  leaf.  The  height  to  which  sap  may  thus  travel 
is  sometimes  very  considerable.  In  the  case  of  the  giant 
trees  of  California,  for  instance,  the  distance  from  the  root 
hairs  to  the  leaves  amounts  to  hundreds  of  feet,  and  the  work 
done  in  transporting  the  liquid  to  this  height  is  great.  It  is 
interesting  to  observe  the  upward  passage  of  the  liquid  in 
the  stem  of  a  plant.  This  may  be  done  by  placing  the  stem 
of  a  white  snowball  or  a  lily  in  a  vase  of  red  ink.  The  red 
solution  passes  up  through  the  stem  and  colors  the  flower. 
The  stem  of  a  plant  is  a  system  of  tubes  formed  by  con- 
tinuously connected  cells,  some  of  which  carry  simple  com- 
pounds in  solution  to  the  leaf,  while  others  carry  food,  made 
in  the  leaf,  back  to  the  root. 

It  is  fortunate  for  the  farmer  and  for  the  food  and  clothing 
supply  of  all  mankind  that  the  plant  derives  more  material 
for  its  solid  substance  from  the  air  than  from  the  soil.  In 
every  hundred  pounds  of  dry  plant  material  there  are  usually 
less  than  three  pounds  that  have  come  from  the  soil.  The 
grains  of  corn,  wheat,  rye,  and  rice  consist  chiefly  of  starch. 
Other  plants,  such  as  the  sugar  beet,  are  rich  in  sugar,  while 
seeds  like  flax  and  cotton  contain  much  oil  and  fat.  Starch, 


PLANT  LIFE  AND  WHAT  IT  PRODUCES       245 

sugar,  oil,  and  many  other  substances  in  plants  are  made 
in  the  leaves  from  the  carbon  dioxide  taken  from  the  air, 
and  the  water,  nitrogen,  phosphorus,  potassium,  and  other 
elements  which  are  absorbed  from  the  soil  in  the  form  of 
salt  solutions  by  the  roots,  as  already  explained.  The 
carbon  dioxide  of  the  air  enters  the  leaf  through  very  small 
openings,  most  of  which  are  located  on  the  under  side  of  the 
leaf.  It  then  passes  into  the  cells,  where  it  comes  into  contact 
with  chlorophyll,  the  substance  to  which  the  leaf  owes  its 
green  color.  Here  a  wonderful  chemical  change  takes  place, 
for  when  the  sun  is  shining  on  the  leaf  the  carbon  dioxide  and 
some  of  the  water  in  the  cells  act  on  each  other,  forming  starch 
and  oxygen.  The  latter  gas  is  exhaled  by  the  leaf.  The 
chemical  equation  expressing  this  change  has  already  been 
given  in  Chapter  IX,  which  see.  Thus  it  is  that  carbon  is 
taken  from  the  air  and  retained  by  the  plant.  The  starch 
and  sugars  formed  in  the  leaf  are  plant  food.  All  parts  of 
the  plant,  including  the  stem,  branches,  leaves,  and  roots,  are 
nourished  by  food  formed  in  this  leaf  laboratory  from  the  ele- 
ments gathered  from  the  air,  the  soil,  and  water.  The  forma- 
tion of  chlorophyll  and  the  conversion  of  carbon  dioxide  and 
water  into  oxygen,  starch,  and  sugar  cannot  take  place  without 
sunlight.  The  plant  is  like  a  machine  run  by  a  motor,  the  sun. 
All  parts  of  the  machine  may  be  perfect  and  in  readiness, 
but  work  will  not  proceed  unless  the  motor  is  in  action. 

It  has  previously  been  stated  that  water  evaporates  from 
the  surface  of  the  leaf.  It  requires  a  great  deal  more  water 
to  carry  food  from  the  roots  to  the  leaf  than  finally  remains 
as  an  integral  part  of  the  tissues  of  the  plant.  This  surplus 
water  is  transpired  or  given  off  by  evaporation  from  the 
leaves,  and  is  thus  returned  to  the  air.  Plants  use  several 
hundred  pounds  of  water  in  making  a  single  pound  of  dry  solid 
matter.  Most  plants  thrive  best  when  they  have  much 


246  CHEMISTRY  AND  DAILY  LIFE 

sunshine  and  frequent  showers.  In  wet  seasons  they  may 
suffer  from  want  of  sunlight,  and  in  dry  seasons  from  lack  of 
water.  The  food  prepared  in  the  leaf  goes  to  all  parts  of  the 
plant  in  the  form  of  sap.  It  passes  through  the  soft  fibrous 
layer  called  the  cambrium,  which  is  between  the  hard  outer 
bark  of  the  tree  and  the  woody  trunk.  It  is  diffused  through- 
out the  plant  and  causes  the  cells  that  compose  it  to  increase 
in  size  and  number ;  that  is,  it  causes  the  plant  to  grow.  This 
sap  may  be  obtained  in  large  quantities  from  some  trees, 
as,  for  instance,  from  the  sugar  maple,  which  is  the  source 
of  maple  sugar  and  maple  sirup. 

The  leaf,  which  is  the  world's  food  laboratory,  gives  off 
oxygen  in  the  sunlight  as  it  synthesizes  starch  from  carbon 
dioxide  and  water.  But  in  the  absence  of  sunlight  the  leaf 
exhales  carbon  dioxide.  It  really  requires  oxygen  to  live,  and 
breathes  in  that  element  just  as  animals  do.  But  during  the 
time  that  the  light  falls  upon  the  leaf,  the  carbon  dioxide 
that  would  be  exhaled  is  utilized  instead,  in  making  starch 
and  sugar.  Consequently  only  in  the  absence  of  sunlight, 
that  is,  when  the  workshop  of  the  leaf  is  closed,  does  one 
really  become  aware  of  the  fact  that  the  plant  breathes  in 
and  uses  oxygen,  and  gives  off  carbon  dioxide  just  as  an 
animal  does. 

The  plant  is  the  source  of  food  for  all  animals,  including 
man.  Man  usually  eats  some  meat,  but  this  is  derived  from 
an  animal  which  either  received  its  nourishment  from  other 
flesh  or  from  vegetable  materials.  In  all  cases,  the  ultimate 
source  of  food  is  the  plant.  The  food  materials  produced 
by  plants  may  be  divided  into  two  great  classes :  (1)  the 
non-nitrogenous,  and  (2)  the  nitrogenous.  The  first  group 
includes  the  carbohydrates  and  fats,  while  the  second  group, 
as  the  name  implies,  consists  of  nitrogen-containing  bodies 
of  which  the  proteins  are  by  far  the  most  important. 


PLANT  LIFE  AND  WHAT  IT  PRODUCES       247 


The  carbohydrates,  as  already  stated  in  Chapter  IX, 
include  the  starches,  sugars,  gums,  pectins,  celluloses,  and  closely 
related  bodies.  These  form  by  far  the  largest  proportion  of  the 
organic  compounds  in  the  plant.  In  many  plants  and  food 
materials  the  carbohydrates  are  present  largely  as  starch. 
About  75  to  80  per  cent  of  the  dry  matter  stored  in  a  farmer's 
haymow  and  grain  bins  is  made  up  of  carbohydrates.  The 
activities  of  plant  life  are  largely  devoted  to  the  production 
of  carbohydrates ;  and  their  consumption  by  animals  is  cor- 
respondingly extensive.  It  should  be  remembered  that  these 
compounds  are  made  of  oxygen,  hydrogen,  and  carbon,  which 
are  derived  wholly  from  the  air  and  water.  The  chemist  in 
his  analysis  of  plant  tissues  always  separates  the  cellulose 
from  the  rest  of  the  carbohydrates,  as  being  of  little  value 
to  animals.  This  crude  cellulose  he  calls  crude  fiber,  and 
to  the  rest  of  the  car- 
bohydrates he  gives 
the  name  nitrogen-free 
extract. 

Starch  is  a  widely 
distributed  and  abun- 
dant constituent  of  vege- 
table tissue.  It  is  found 
in  all  the  green  parts 
of  leaves,  and  accumu- 
lates in  those  organs  of 
plants  which  serve  as 
stores  of  reserve  mate- 
rial. It  occurs  espe- 
cially in  roots,  fruits,  and  seeds.  In  some  seeds  as  much  a^ 
60  to  70  per  cent  is  present.  Probably  only  water  and  cellu- 
lose are  more  abundant  than  starch  in  the  vegetable  world. 
Starch  does  not  exist  in  solution  in  the  sap,  but  it  is  found 


FIG.  86.  —  Potato  starch  grains. 


248 


CHEMISTRY  AND   DAILY  LIFE 


in  the  interior  of  plant  cells  in  the  form  of  minute  grains, 
which  have  a  shape,  size,  and  structure  characteristic  of  the 
seed  in  which  they  are  found  (see  Figs.  86,  87,  and  88). 
Potato  starch  grains  are  large,  being  about  0.003  of  an  inch 
in  diameter,  while  those  of  wheat  are  smaller,  about  0.001  of 
an  inch  in  diameter,  and  resemble  in  outline  a  thick  burn- 
ing glass.  These  differences  in  the  size  and  shape  of  starch 

grains  furnish  the  most 
important  means  of  de- 
tecting adulterations  of 
one  grain  with  another, 
as,  for  example,  when 
corn  flour  is  mixed 
with  wheat  flour.  Un- 
less changed  by  some 
chemical  means,  starch 
is  not  soluble  in  water. 
Prolonged  treatment 
with  hot  water  causes 
the  starch  grains  to 
swell  and  burst,  thus 
forming  starch  paste,  which  is  used  as  an  adhesive.  Starch 
is  spoken  of  as  potato  starch,  wheat  starch,  rice  starch,  etc., 
according  to  the  name  of  the  plant  from  which  it  has  been 
obtained.  Potato  starch  is  prepared  by  rasping  the  potato 
with  water  and  passing  the  product  through  fine  sieves. 
The  coarse  particles  remain  on  the  sieve,  while  the  starch 
passes  through  the  meshes  in  suspension  in  water.  The 
turbid  liquid  is  allowed  to  stand  in  vats  till  the  starch  has 
settled  to  the  bottom.  All  kinds  of  starch  have  the  common 
property  of  being  colored  blue  when  treated  with  iodine. 
Starch  is  used  as  human  food,  and  it  is  also  extensively  ejn- 
ployed  in  laundries.  Applied  as  a  paste  to  linen,  it  causes 


FIG.  87.  —  Pea  starch  grains. 


PLANT  LIFE  AND  WHAT  IT  PRODUCES       249 

the   threads   to   adhere   together,   thus   making  the  fabric 

stiffer.     The  hot  iron  of  the  laundry  converts  some  of  the 

starch  to  dextrins,  which  impart  a  gloss  to  the  linen  or  cotton 

fabrics.     Dextrins  have 

a  sweet  taste,  and  they 

are  the  same  substances 

that    are    formed    from 

starch    when    the    loaf 

of  bread  is  baked.     In 

the  crust   and  in  toast 

they     are     particularly 

abundant. 

The  sugars  are  very 
valuable  carbohydrates, 
although  they  occur  in 
plants  in  less  amounts 

FIG.  88.  —  Wheat  starch  grains. 

than  the  starches.    I  hey 

are  found  only  in  small  quantities  in  hays,  while  in  seeds 
their  amounts  are  scarcely  appreciable.  In  fruits  sugars  are 
more  abundant.  They  are  also  found  in  solution  in  the  sap 
of  young  plants,  hence  the  sweet  taste  of  this  juice.  The 
most  important  sugar,  commercially  considered,  is  sucrose,  also 
known  as  cane  sugar  or  beet  sugar  (see  Chapter  IX).  As  a 
human  food  it  is  widely  used,  and  its  manufacture  and  sale 
constitute  a  prominent  industry.  In  some  plants  sucrose 
occurs  in  abundance,  as  in  the  sugar  cane,  which  grows  in 
the  south.  The  sugar  beet  which  thrives  in  northern  climes 
is  to-day  a  very  important  source  of  sugar.  Sucrose  also 
exists  in  sorghum  and  in  considerable  quantities  in  ordinary 
field  corn,  sweet  potatoes,  and  pineapples.  Fruits  generally 
contain  an  appreciable  amount  of  this  sugar  mixed  with 
other  sugars  and  organic  acids.  As  already  pointed  out  in 
Chapter  IX,  dextrose,  also  known  as  glucose  and  grape  sugar, 


250  CHEMISTRY  AND  DAILY  LIFE 

is  a  wry  important  article  of  commerce,  usually  appearing  on 
the  market  in  the  form  of  certain  candies  and  sirups,  though 
it  is  also  present  to  some  extent  in  molasses,  which  see.  Corn 
sirup  is  glucose  prepared  by  the  usual  method,  i.e.  by  heat- 
ing starch  with  dilute  sulphuric  acid ;  see  Chapter  IX,  where 
the  behavior  of  dextrose  and  other  sugars  toward  Fehling's 
solution  is  also  described.  Fructose  occurs  in  fruits,  and 
maltose  is  formed  from  starch  when  seeds  germinate.  These 
sugars  too  have  been  described  in  Chapter  IX. 

The  pectins  are  closely  related  to  the  carbohydrates. 
They  are  the  cause  of  the  jellying  of  fruits  such  as  apples  and 
currants.  They  exist  in  greater  abundance  in  fruit  that  is 
not  quite  ripe,  and  consequently  this  is  commonly  selected 
for  jelly  making  in  preference  to  ripe  fruit.  When  such  un- 
ripe fruits  are  cooked,  the  pectins  take  up  water  and  are 
changed  into  gelatinous  bodies  which  set  to  a  firm  mass  on 
cooling. 

The  tough  or  woody  parts  of  plant  tissues  consist  of  cellu- 
lose. Wood,  cotton,  linen,  hemp,  flax,  etc.,  when  freed  from 
mineral  matter,  are  almost  pure  cellulose,  as  already  stated  in 
Chapter  IX.  Cellulose  is  insoluble  in  water,  and  is  not  readily 
attacked  even  by  strong  acids,  as  previously  explained,  see 
Chapter  IX.  In  tables  of  the  results  of  food  analysis,  the 
term  crude  fiber  is  commonly  used.  This  material  is  largely 
cellulose. 

Plant  tissues  also  contain  fats  and  oils,  and  what  has  been 
said  in  Chapter  IX  as  to  the  chemical  nature  of  such  com- 
pounds should  be  carefully  reviewed  in  this  connection.  It 
will  be  recalled  that  though  fats  and  oils,  like  the  carbohy- 
drates, consist  of  carbon,  hydrogen,  and  oxygen,  yet  they  are 
an  entirely  different  class  of  compounds.  The  fats  and  oils 
are  mixtures  of  esters  of  oleic,  stearic,  palmitic,  and  other  fatty 
acids  with  glycerine  acting  as  the  base.  The  glycerine  is  set 


PLANT  LIFE  AND  WHAT  IT  PRODUCES       251 

free  when  the  fats  are  heated  with  caustic  alkalies,  as  in  the 
process  of  soap  making.  Fats  and  oils  contain  a  very  much 
higher  percentage  of  carbon  than  the  carbohydrates.  The 
organic  fats  and  oils  met  in  common  life  are  partly  of  animal 
and  partly  of  vegetable  origin.  So  tallow,  lard,  butter,  goose 
and  chicken  grease  are  of  animal  origin  ;  while  olive  oil,  cotton- 
seed oil,  linseed  oil,  etc.,  are  obtained  from  plants.  Fats  and 
oils  are  readily  soluble  in  either  chloroform,  carbon  tetrachloride, 
carbon  bisulphide,  gasoline,  or  ether.  This  fact  is  utilized  in 
removing  grease  spots  from  clothes,  but  also  in  determining  the 
fat  content  of  various  products  by  means  of  chemical  analysis. 
When  a  ground  food  material  of  either  animal  or  vegetable 
origin  is  leached  with  ether,  gasoline,  or  chloroform,  the  fats 
and  oils  it  contains  are  dissolved.  When  afterward  the  clear 
solutions  thus  obtained  are  carefully  evaporated  to  dryness, 
the  residue  which  remains  consists  of  the  fats  and  oils  plus 
such  minor  amounts  of  other  substances  as  are  slightly 
soluble  in  the  solvent  employed.  When  seeds  are  ground  and 
then  extracted  with  ether,  the  material  dissolved  in  the  latter 
consists  of  almost  pure  fats  and  oils ;  but  when  hays,  straws, 
arid  green  plant  tissues  are  thus  treated  with  ether,  the  extract 
contains  the  fats  and  oils  plus  other  substances,  like  chloro- 
phyll, which  are  also  soluble  in  ether.  In  tables  showing  the 
composition  of  foods  there  is  commonly  a  column  headed  ether 
extract ;  the  figures  in  this  column  represent  practically  pure 
fat  in  the  case  of  seeds,  but  in  the  case  of  hay  or  straw  they 
will  represent  fat  plus  minor  impurities  that  have  also  been 
extracted  along  with  the  fat.  The  amounts  of  fats  and  oils 
found  in  plant  tissues  vary  greatly  with  the  nature  of 
the  plant  and  also  with  the  parts  of  any  one  particular 
plant.  In  general,  the  seed  contains  much  more  fat  than  the 
leaf,  stem,  or  root.  Fleshy  roots  like  potatoes  and  beets,  for 
example,  contain  but  little  fat.  The  common  farm  seeds,  such 


252  CHEMISTRY  AND  DAILY  LIFE 

as  corn,  oats,  barley,  rye,  and  wheat  contain  from  two  to 
five  per  cent  fat;  while  flaxseed  (linseed),  cotton  seed,  and 
peanuts  run  as  high  as  thirty  to  forty-five  per  cent.  The 
oils  from  some  of  the  seeds  are  of  great  commercial  value. 
Thus  cottonseed  and  olive  oils  are  important  articles  of  food, 
while  linseed  oil  (compare  Chapter  XII)  is  used  in  enormous 
quantities  in  the  paint  industries. 

Some  plants  produce  acids  in  abundance.  In  Chapter  V 
attention  has  already  been  called  to  this  fact.  Thus  citric 
acid  occurs  in  lemons  and  other  citrous  fruits  ;  malic  acid  is 
present  in  sour  apples,  currants,  mountain  ash  berries,  etc.; 
tartaric  acid  gives  the  tart  taste  to  grapes ;  and  oxalic  acid 
may  be  found  in  rhubarb,  oxalis,  and  the  jack-in-the-pulpit. 
The  ordinary  farm  seeds,  roots,  and  fodders,  however,  are  free 
from  acids ;  and  it  is  only  when  they  are  subjected  to  fermenta- 
tion that  acids  are  formed  from  them.  A  familiar  example  of 
this  is  the  production  of  silage.  Here  fermentation  changes 
the  sugars  of  the  fresh  corn  mainly  to  acetic  and  lactic  acids 
(see  Chapter  IX  for  a  description  of  these),  and  it  is  the 
volatile  acids  that  give  to  silage  its  sour  smell.  The  sour 
smell  of  the  ill-kept  kitchen  garbage  pail  is  also  due  to  volatile 
organic  acids  produced  by  fermentation.  What  has  been 
said  about  organic  acids  in  Chapter  IX  should  be  carefully 
reviewed  here. 

The  proteins,  which  are  very  complex  compounds,  are 
absolutely  necessary  to  the  life  of  every  cell.  They  consist 
of  carbon,  hydrogen,  oxygen,  nitrogen,  sulphur,  and  some- 
times phosphorus  about  in  the  proportions  indicated  in 
Chapter  IX.  It  is  for  the  purpose  of  building  up  these  pro- 
teins that  the  root  of  the  plant  must  have  access  to  nitrates, 
sulphates,  and  phosphates.  If  any  one  of  these  is  lacking,  the 
plant  ceases  to  grow.  Just  as  there  are  various  carbohydrates, 
so  there  are  several  kinds  of  proteins.  A  familiar  one  is  the 


PLANT  LIFE  AND  WHAT   IT  PRODUCES        253 

albumen  of  the  egg.  This  will  dissolve  in  water  and  coagu- 
late when  heated.  The  process  of  the  coagulation  of  albumen 
is  really  a  remarkable  change  which  is  by  no  means  fully 
understood.  Some  very  common  matters  of  observation 
really  depend  upon  the  chemical,  physical,  and  physiological 
properties  of  the  proteins.  So,  for  example,  the  farmer's  boy 
secures  a  tenacious  cud  of  gum  from  fresh  wheat  kernels, 
the  housewife  watches  the  strings  of  coagulated  albumen 
separate  from  the  cold  water  extracts  of  fresh  lean  beef  when 
the  liquid  is  boiled,  or  observes  the  white  mass  harden  as 
the  egg  is  dropped  into  boiling  water.  The  seeds  of  plants 
are  richer  in  proteins  than  the  stems.  Wheat  grain  contains 
from  eleven  to  twelve  per  cent  of  protein,  while  in  the  straw 
there  are  only  from  three  to  four  per  cent.  Some  seeds  are 
particularly  rich  in  proteins.  So,  for  instance,  peas  and 
beans  may  contain  from  sixteen  to  twenty  per  cent  of  protein. 
The  proteins  that  are  soluble  in  water  are  called  albumins. 
They  are  found  in  the  juice  of  plants,  but  also  in  blood, 
milk,  and  especially  in  eggs.  The  globulins  are  another  class 
of  proteins  which  occur  most  abundantly  in  seeds.  While 
they  are  insoluble  in  water,  they  may  be  dissolved  by  treating 
the  ground  seed  with  a  five  per  cent  solution  of  common  salt. 
There  are  numerous  other  proteins  which  cannot  be  mentioned 
here.  When  heated  with  soda  lime  all  proteins  give  off  ammonia, 
which  fact  is  frequently  used  to  detect  their  presence.  Certain 
color  reactions  to  which  attention  will  be  called  in  connection 
with  the  laboratory  experiments  (Chapter  XXII)  also  serve 
for  this  purpose. 

In  young  growing  plant  tissue  there  is  found  a  group  of 
nitrogenous  substances  called  "  amides."  In  complexity  of 
chemical  composition,  these  lie  between  the  nitrates  and  the 
proteins.  It  is  in  the  form  of  these  amides  that  the  nitrogen 
of  the  growing  plant  is  carried  around  to  the  various  cells. 


in 


254  CHEMISTRY  AND   DAILY  LIFE 

Nitrogenous  compounds  of  this  kind  are  far  more  abundant 
hays  and  roots  than  in  seeds.  A  considerable  part  of  the  ni- 
trogen contained  in  plants  cut  for  hays,  like  timothy,  the 
clovers,  and  alfalfa,  is  in  this  form. 

QUESTIONS 

1.  What  name  is  given  to  the  substance  common  to  all  living 
matter  ?    In  what  is  it  contained  ? 

2.  What  name  is  given  to  the  living  part  of  the  seed  ?    What 
three  things  are  necessary  to  make  a  seed  sprout  ? 

3.  What  effect  does  temperature  have  on  the  germination  of 
seeds  ? 

4.  How  do  seeds  differ  in  the  way  they  come  through    the 
ground  ? 

5.  What  is  the  action  of  the  root,  and  how  does  food  material 
enter  it  ? 

6.  What  proportion  of  the  solid  substance  of  a  plant  comes  from 
the  air  ? 

7.  What  does  the  leaf  of  a  plant  do  ?    What  substance  in  the  leaf 
is  especially  active  in  sunlight  ? 

8.  What  is  the  function  of  sunlight  in  making  starch  ?     Com- 
pare the  breathing  of  a  plant  with  that  of  an  animal. 

9.  Name  three  substances  that  are  carbohydrates.    How  would 
you  test  for  starch  ? 

10.  How  does  cane  sugar  differ  from  starch  ?    What  substance  in 
fruits  causes  their  jellying  ?    How  does  cellulose  differ  from  starch 
in  its  properties  ? 

11.  What  elements  are  contained  in  fats  ?    What  dissolves  fats  ? 
What  does  the  ether  extract  in  the  process  of  food  analysis  contain  ? 

12.  What  elements  are  found  in  protein  ?    Why  is  nitrogen  such 
an  important  element  in  the  soil  ?    Name  a  protein. 

13.  What  two  acids  are  found  in  silage  ? 


CHAPTER  XVIII 
THE   ANIMAL   AND   ITS   FEED 

ANIMALS  cannot  feed  on  the  mineral  matter  in  the  soil 
nor  the  carbon  dioxide  in  the  air.  Plants  live  on  both. 
The  chief  usefulness  of  plants  to  man  lies  in  their  ability  to 
convert  the  minerals  of  the  soil  and  the  carbon  dioxide  of  the  air 
into  substances  that  will  nourish  him  and  his  servants  —  the 
domestic  animals.  Plants  form  the  natural  food  of  the  animal 
of  the  farm. 

The  bodies  of  animals  consist  of  flesh,  fat,  bones,  blood, 
teeth,  hair,  etc. ;  nevertheless,  the  chemist  would  say  that 
the  same  classes  of  substances  are  present  in  the  bodies  of  ani- 
mals as  are  found  in  plants ;  namely,  water,  ash  or  mineral 
matter,  proteins,  fats,  and  carbohydrates.  Each  of  these 
substances  from  the  plant  may  be  utilized  by  the  animal  in 
forming  somewhat  similar  materials  in  its  body.  But  plants 
contain  important  substances,  like  cellulose  and  the  starches, 
which  are  not  present  in  animals.  The  starches  represent 
one  of  the  most  important  foods  of  animals.  Instead  of  adding 
starch  to  its  own  body  unchanged,  the  animal  converts  it  into 
animal  fat,  or  uses  it  as  a  fuel  to  produce  animal  heat.  Cel- 
lulose, being  a  very  resistant  material,  is  utilized  by  animals  as 
food  only  to  a  slight  extent.  Most  of  it  that  is  eaten  passes  out 
of  the  intestine  as  a  part  of  the  feces.  More  than  half  of  the 
weight  of  the  body  of  an  animal  consists  of  water ;  and  besides 
the  water  which  animals  drink,  they  eat  food  which  is  in  a  large 
measure  composed  of  water. 

255 


256  CHEMISTRY  AND  DAILY  LIFE 

The  dry  mineral  matter  which  remains  when  the  bodies 
of  plants  or  animals  are  burned  is  called  the  ash.  The  nature 
of  plant  ash  has  already  received  attention.  The  ash  of  an 
animal  comes  mainly  from  its  skeleton.  While  the  skeleton 
usually  represents  only  about  8  per  cent  of  the  total  weight 
of  an  animal,  nevertheless  95  per  cent  of  all  of  the  ash  of  the 
body  is  in  this  earthy  framework,  which  consists  principally 
of  calcium  phosphate.  The  ash  of  the  animal  always  contains 
all  of  the  mineral  elements  that  are  necessary  for  the  growth 
of  the  plant.  The  same  mineral  constituents  that  a  plant 
must  have  in  order  to  be  able  to  develop  are  also  required 
by  the  animal  in  its  process  of  growth.  Animals  generally 
contain  more  sodium  and  chlorine  than  plants,  for  the  blood 
is  rich  in  common  salt.  There  is  generally  an  abundance  of 
ash  in  the  common  feeds  to  supply  all  of  the  mineral  matter  the 
animal  needs.  But  pigs  fed  on  grain  alone,  without  access  to 
a  pasture,  may  to  advantage  receive  wood  ashes  in  their  feed,  for 
this  will  furnish  them  more  lime,  and  thus  aid  in  bone  forma- 
tion and  other  ways.  Laying  hens  having  no  opportunity 
to  range  need  extra  mineral  matter  in  the  form  of  oyster  shells, 
bone,  or  limestone.  These  should  be  suitably  ground.  They 
are  used  by  the  hen  in  making  the  shell  of  the  egg. 

The  animal  is  essentially  a  protein  structure,  while  the  plant 
is  a  carbohydrate  structure;  for  the  animal  is  rich  in  proteins, 
and  the  plant  usually  does  not  contain  so  much  of  these 
compounds.  The  proteins  of  the  plant  are  used  by  the  ani- 
mal to  make  lean  meat,  muscle,  blood,  nerves,  brain,  hoofs, 
hair,  and  the  casein  of  milk.  It  is  also  very  probable  that 
fat,  which  is  non-nitrogenous  in  character,  may  be  formed 
from  proteins ;  but  this  question  is  still  disputed.  Proteins 
serve  as  a  source  of  energy.  In  the  case  of  a  dog  that  eats 
only  meat,  probably  the  greater  part  of  the  protein  eaten  is 
not  stored,  but  used  as  fuel  for  producing  body  heat.  An 


THE  ANIMAL  AND   ITS  FEED  257 

animal  can  get  along  without  carbohydrates  or  fat,  but  it  must 
have  a  certain  amount  of  protein  in  its  daily  ration,  for  the  cells 
of  the  body  are  constantly  losing  nitrogen,  which  can  only  be 
replaced  by  protein. 

The  fats,  it  will  be  recalled,  are  free  from  nitrogen.  Those 
consumed  with  the  food  may  be  deposited  in  the  tissues  of 
the  body  without  essential  change.  Small  deposits  of  fat, 
indeed,  occur  in  every  organ  and  cell,  but  the  amount  held 
in  reserve  varies  greatly  with  the  nutritive  condition  of  the 
animal.  So  a  lazy,  overfed  pig  will  have  great  reserves 
of  fat,  while  a  hard-worked  horse  will  not  show  such  reserves. 
The  fat  of  the  food  is  either  burned  in  the  body  to  furnish 
heat  and  mechanical  energy,  or  it  is  stored  as  reserve  material. 

The  carbohydrates,  especially  starch,  sugars,  and  cellulose, 
form  by  far  the  largest  part  of  all  food  of  vegetable  origin.  They 
are  not  stored  permanently  in  the  body,  but  as  they  are  oxi- 
dized in  the  system  they  furnish  heat  or  mechanical  work. 
There  is  always  a  small  amount  of  sugar  in  the  blood,  —  less 
than  one  per  cent,  —  but  after  a  meal  the  liver  and  muscles 
contain  an  abundance  of  the  carbohydrate  glycogen,  which  is 
really  animal  starch.  But  this  is  only  a  small  portion  of  the 
animal's  daily  intake  of  carbohydrates.  When  consumed  in 
excess  of  the  immediate  requirements,  carbohydrates  are 
changed  to  fats  and  stored  as  such.  As  a  practical  illustration 
of  this  truth  may  be  mentioned  the  well-known  value  of  corn 
meal,  which  is  particularly  rich  in  starch,  as  a  fattening  food. 

The  animal  body  performs  work.  Even  an  idle  horse  ex- 
pends some  energy  in  the  circulation  of  the  blood  and  the 
digestion  of  food.  The  more  work  the  horse  does,  the  greater 
the  amount  of  energy  he  must  expend  ;  and  so  the  horse  uses 
a  part  of  the  energy  represented  in  the  food  he  eats  for  the 
production  of  motion,  just  as  a  steam  engine  uses  coal  in 
furnishing  power.  In  addition,  a  certain  amount  of  food  is 


258  CHEMISTRY  AND   DAILY  LIFE 

oxidized  in  the  animal  body  daily  to  maintain  its  temperature. 
The  temperature  of  domestic  animals  and  man  is  about  38°  C., 
which  is  much  above  the  prevailing  temperature  of  any 
climate,  and  to  maintain  this  temperature  fuel  is  required. 
All  of  the  foodstuffs  —  carbohydrates,  fats,  and  proteins  — 
may  serve  as  fuel  in  the  animal  body  to  produce  heat  and 
other  forms  of  energy ;  but  when  fats  and  carbohydrates  are 
available,  the  proteins  of  the  tissues  are  not  normally  burned 
for  this  purpose.  Only  when  carbohydrates  and  fats  are  lack- 
ing will  the  animal  burn  up  its  proteins ;  and  so,  because  the 
latter  are  relatively  expensive,  it  is  more  economical  to  have 
a  plentiful  supply  of  fats  and  carbohydrates  in  the  diet  as  sources 
of  heat  and  other  energy,  providing  sufficient  protein,  however, 
when  new  tissues  are  to  be  built,  as  in  growth,  or  when  milk 
is  to  be  produced,  as  in  the  case  of  the  milch  cow.  A  work- 
ing horse  needs  some  protein,  but  uses  mainly  carbohydrates 
and  plant  fats  for  the  production  of  heat  and  work.  A 
pound  of  fat  will  produce  2.4  times  as  much  heat  as  a  pound 
of  carbohydrates;  which  will  not  seem  strange  when  it  is 
remembered  that  fats  contain  relatively  much  more  carbon 
than  is  present  in  carbohydrates.  A  pound  of  protein  will 
produce  about  the  same  amount  of  heat  as  a  pound  of  car- 
bohydrates. 

The  important  process  by  which  the  food  of  animals  or 
man  is  rendered  capable  of  being  absorbed  into  the  system 
and  used  in  building  up  or  renewing  the  tissues  of  the  body 
is  called  digestion.  So,  for  instance,  corn  meal  or  hay  can- 
not directly  be  transferred  to  the  blood.  These  must  first 
be  brought  into  solution  before  they  can  pass  out  of  the  di- 
gestive tract  into  the  blood  and  lymph ;  for  just  as  no  solid 
particles  can  pass  into  a  plant  through  its  rootlets,  so  no  solid 
particles  can  pass  through  the  walls  of  the  alimentary  canal 
into  the  body.  Furthermore,  just  as  the  rootlets  of  a  plant 


THE  ANIMAL  AND   ITS   FEED  259 

give  off  carbon  dioxide  which  aids  the  soil  water  in  dissolving 
plant  food,  so  the  walls  of  the  alimentary  canal  secrete  certain 
substances  which  aid  in  liquefying  food  so  that  it  may  be 
absorbed.  The  process  of  getting  food  ready  for  absorption 
is  partly  a  mechanical  one,  but  it  consists  mainly  of  a  series 
of  chemical  changes  which  are  produced  to  a  large  extent  by 
the  action  of  bodies  called  enzymes.  These  are  peculiar  sub- 
stances which  are  produced  by  all  living  plant  or  animal 
cells.  They  are  in  general  non-crystalline,  slimy,  soluble 
substances  containing  the  same  essential  elements  as  the 
proteins;  but  their  exact  composition  is  still  unknown. 
Enzymes,  also  called  unorganized  ferments,  have  the  power 
to  bring  about  certain  complex  chemical  changes  at  ordinary 
temperatures.  For  example,  the  enzyme  in  the  saliva  causes 
starch  to  change  to  the  soluble  sugar,  maltose.  If  starch  were 
to  be  changed  to  sugar  in  the  laboratory,  the  chemist  would 
have  to  add  an  acid  and  apply  heat.  Another  peculiarity 
is  that  an  enzyme  that  can  act  on  starch  has  no  effect  on 
proteins  or  on  fat.  So  the  starch-splitting  enzyme  has  no 
action  on  the  casein  of  milk.  Enzymes  are  easily  destroyed 
by  heat.  The  temperature  of  boiling  water  stops  their  action. 
The  process  of  digestion  begins  in  the  mouth.  The  first 
step  is  mastication,  by  which  the  food  is  subdivided  and 
crushed  by  the  action  of  the  teeth  and  at  the  same  time  well 
mixed  with  saliva.  The  latter  is  a  very  dilute  solution  which 
turns  litmus  paper  blue  and  contains  the  enzyme  ptyalin, 
which  has  the  power  of  converting  the  insoluble  starch  of  the 
food  to  soluble  sugar.  This  change  begins  in  the  mouth  and 
continues  in  the  stomach  for  a  time.  But  when  the  acid 
juice  of  the  stomach  comes  into  contact  with  the  ptyalin, 
this  enzyme  ceases  its  action.  Proteins  and  fats  are  not 
attacked  by  the  juice  of  the  mouth.  It  is  estimated  that  an 
ox  or  a  horse  secretes  one  hundred  pounds  of  saliva  daily.  This 


260 


CHEMISTRY  AND  DAILY  LIFE 


fluid  also  prepares  the  food  for  swallowing.  After  mastica- 
tion the  food  passes  down  the  gullet  into  the  stomach.  In  the 
case  of  man,  the  horse,  and  the  pig,  the  stomach  is  a  single  sac, 
and  true  digestion  begins  here  at  once.  In  ruminants  (cud 
chewers),  like  the  ox  and  the  sheep,  the  stomach  consists  of  four 
sacs,  and  not  until  the  fourth  one  is  reached  by  the  food  does 
true  digestion  begin.  These  sacs  are  used  for  storage,  and 
they  are  rather  complicated  in  structure.  The  large  paunch 

of  the  ox,  which  is 
the  first  compartment 
reached  by  the  food 
after  it  leaves  the 
mouth,  has  a  capacity 
of  50  to  60  gallons.  It 
is  in  the  paunch  that 
the  food  is  stored ;  and 
because  of  its  coarse 
nature,  it  is  returned 
to  the  mouth  later  for 
more  thorough  dividing 
and  mixing  with  saliva. 
This  is  what  is  called 
"  chewing  the  cud." 
The  action  of  the  saliva  on  the  food  in  the  paunch  is  thus 
continued  much  longer  than  would  be  the  case  in  the  true 
stomach  of  man  or  the  pig.  When  the  food  reaches  the 
fourth  stomach  in  the  ox,  or  the  first  one  in  the  pig,  true 
digestion  begins.  The  active  digestive  fluid  comes  from  cells 
in  the  mucous  membrane  that  lines  the  stomach.  It  is 
a  watery  fluid  containing  various  salts,  free  hydrochloric 
acid,  and  the  two  enzymes,  pepsin  and  rennin.  This  com- 
bination  of  pepsin  and  acid  is  the  effective  agent  in  the  diges- 
tion. It  acts  on  the  proteins  of  the  food,  dissolving  them 


FIG.  89.  —  Stomach  of  a  horse. 


THE  ANIMAL  AND   ITS  FEED 


261 


by  converting  them  into  simple  nitrogenous  bodies.  This 
enzyme,  like  ptyalin,  works  best  at  the  body  temperature, 
38°  C.  It  is  said  that  the  stomach  juice  of  the  sheep  has 
a  low  acidity,  0.1  per 
cent,  while  that  of  the 
dog  is  much  higher. 
Chemically  the  results 
accomplished  in  the  stom- 
achs of  all  farm  animals 
are  the  same;  thai  is, 
the  proteins  are  changed 
to  simple  soluble  nitrog- 
enous substances.  The 
utilization  of  coarse 
feed  by  the  horse  is  not 
as  complete  as  by  the 
ox,  for  the  reason  that 
with  the  former  there  is 

no  preliminary  remastication  before  the  food  material  comes 
into  contact  with  the  gastric  juice.  The  purpose  of  the 
rennin  in  the  stomach  juice  is  to  curdle  the  milk.  Here  rennin 
acts  exactly  the  same  as  when  it  is  used  in  making  cheese. 
As  milk,  the  sole  source  of  nutriment  for  the  young,  is  a 
fluid  which  cannot  be  directly  absorbed,  it  would  not  be  so 
completely  digested  if  it  were  not  first  converted  to  a  solid 
mass,  for  it  would  pass  through  the  intestine  too  fast.  The 
rennin  curdles  it  and  gives  the  pepsin  a  longer  time  to  act. 

When  the  food  leaves  the  stomach,  it  enters  the  small  in- 
testine. At  this  point  it  is  only  partly  digested.  The  fats 
have  not  been  changed,  and  undoubtedly  a  considerable  part 
of  the  proteins  and  carbohydrates  is  still  to  be  acted  upon. 
The  juice  from  the  pancreas,  which  is  poured  into  the  intestine 
at  a  point  just  below  the  junction  of  the  stomach  and  small 


FIG.  90.  — Stomach  of  a  sheep. 


262  CHEMISTRY  AND   DAILY  LIFE 

intestine,  is  the  active  agent  in  completing  the  solution  of  all 
the  materials  that  can  be  digested.  It  is  a  strongly  alkaline 
solution  and  contains  three  enzymes,  (1)  trypsin,  a  protein- 
splitting  enzyme,  (2)  lipase,  a  fat-splitting  enzyme,  and  (3) 
amylopsin,  a  starch-digesting  enzyme.  By  the  action  of  this 
juice,  the  acid  chyme  from  the  stomach  becomes  alkaline, 
and  the  unattacked  proteins,  fats,  and  carbohydrates  are 
reduced  to  simpler  compounds,  which  are  more  soluble  in 
the  juice  and  capable  of  being  absorbed  through  the  in- 
testinal wall.  The  fat  undergoes  but  little  change,  but  a 
part  of  it  is  converted  to  soap,  the  formation  of  which  helps 
to  hold  the  rest  of  the  fat  in  suspension  as  very  finely  divided 
globules  that  can  be  absorbed. 

The  proteins,  carbohydrates,  and  fats  of  the  food  are 
gradually  digested  by  the  processes  just  described.  Through- 
out  the  length  of  the  long  intestine  absorption  proceeds  rapidly. 
Water,  salts,  and  the  products  of  digestion  pass  from  the 
intestine  into  the  circulating  lymph  and  blood.  The  sugars 
are  carried  to  the  liver,  converted  into  glycogen,  and  stored 
temporarily,  being  doled  out  again  to  the  blood  in  constant 
quantities  to  be  carried  to  the  remotest  cells  of  the  body 
for  fuel.  The  proteins  are  carried  to  all  the  cells  of  the  body, 
where  they  serve  in  the  work  of  repair  and  new  growth.  The 
fats  are  either  deposited  in  the  various  tissues,  or  are  used 
as  food  by  the  hungry  and  moving  muscle  cells. 

In  the  lungs  the  blood  is  supplied  with  oxygen.  Here  purple 
venous  blood  is  changed  to  scarlet  by  the  oxygen  which  it 
absorbs.  At  the  same  time,  a  considerable  quantity  of  car- 
bon dioxide,  which  was  formed  in  the  burning  of  fuel  in  the 
cells,  is  brought  to  the  lungs  by  the  blood  stream  and  given 
up  to  the  air.  Inspired  air  contains  about  21  per  cent  of  oxygen 
and  0.03  per  cent  of  carbon  dioxide,  while  in  expired  air  there 
is  approximately  16.5  per  cent  of  oxygen  and  4-4  Per  ceni  °f 


THE  ANIMAL  AND  ITS  FEED  263 

carbon  dioxide.  Though  oxygen  is  absorbed  in  the  lungs,  it 
is  not  here  that  the  process  of  oxidation  of  the  carbon  and 
hydrogen  content  of  the  food  takes  place.  The  blood  acts 
simply  as  a  carrier  of  oxygen  and  the  combustion  itself  actually 
takes  place  in  the  remote  tissues. 

The  nutrients  of  foods  are  not  wholly  digested.  A  part 
passes  through  the  animal  without  having  been  liquefied  and 
dissolved  by  the  digestive  juices  and  thereby  made  available 
to  the  animal.  Foods  differ  in  this  respect.  Those  rich  in 
cellulose,  such  as  hays,  straws,  and  the  coarse  parts  of  grains, 
will  leave  much  greater  indigested  residues  than  whole  grains 
or  the  interior  parts  of  grains.  Milk  is  completely  digested. 
Animals  likewise  differ  in  their  ability  to  digest  coarse  feeds. 
The  cow  and  the  horse  will  make  better  use  of  hay  and  straw 
than  the  pig.  This  is  mainly  due  to  the  large  storage  appa- 
ratus in  the  former  animals.  Because  of  these  differences  in 
the  digestibility  of  feeds,  the  availability  of  their  nutrients 
naturally  differs.  This  availability  of  the  nutrients  of  foods 
is  called  the  coefficient  of  digestibility.  It  is  the  amount  of 
nutrients  that  the  animal  can  secure  from  a  given  feed.  For 
example,  the  coefficient  of  digestibility  of  the  dry  matter 
of  corn  meal  is  89.6,  and  that  of  timothy  hay  is  57.9.  This 
means  that  in  100  pounds  of  dry  matter  from  corn  meal, 
89.6  pounds  are  available,  while  in  timothy  hay  but  57.9 
pounds  are  available.  These  figures  are  for  the  cow.  Larger 
reference  books  on  the  subject  of  feeds  and  feeding  must 
be  consulted  for  tables  giving  such  coefficients  of  digestibility 
of  foods  for  the  various  domestic  animals. 

A  knowledge  of  the  relative  digestibility  of  the  several 
nutrients  contained  in  the  feeding  material  determines  how 
an  animal  ought  to  be  fed,  that  is,  it  suggests  how  to  make  a 
feeding  standard.  Such  knowledge  has  been  secured  by 
many  experiments  with  animals.  It  has  also  been  found 


264  CHEMISTRY  AND  DAILY  LIFE 

in  practice  that  the  feed  of  an  animal  may  be  varied  within 
fairly  wide  limits,  provided  the  ratio  of  digestible  proteins  to 
all  other  digestible  organic  matter  is  kept  within  certain  limits. 
Protein  has  special  functions  and  less  than  a  certain  quan- 
tity would  limit  growth  or  production.  For  this  reason  the 
ratio  of  protein  to  the  other  nutrients  must  be  held  within  defi- 
nite limits.  It  will  be  recalled  that  fat  and  starch  are  used 
for  fuel,  and  that  a  pound  of  fat  can  produce  2.4  times  as 
much  heat  as  a  pound  of  starch.  The  nutritive  ratio  is 
always  expressed  as  amount  of  protein  to  amount  of  starch, 
including  in  the  starch  the  fat  reduced  to  a  starch  basis.  The 
nutritive  ratio  consequently  becomes : 

The  weight  of  digestible  protein 


The  weight  of  digestible  carbohydrate  +  (digestible  fat  x  2.4) 

For  example,  the  nutritive  ratio  of  corn  meal  is  obtained 
as  follows : 

100  Ib.  contain  7.9  Ib.  digestible  protein. 

66.7  Ib.  digestible  carbohydrates. 
4.3  Ib.  digestible  fat. 

7.9  =          7.9         =     7.9        J^ 

66.7  +  (4.3  X  2.4)  ~  66.7  +  9.32  ~  76.02  ~  9.6 

The  nutritive  ratio  of  corn  meal  is  therefore  1 : 9.6.  This 
means  that  for  every  pound  of  digestible  protein  in  corn  meal 
there  are  9.6  pounds  of  digestible  carbohydrates  and  fat 
equivalent  thereto.  A  wide  ratio  is  one  in  which  there  is  a 
large  amount  of  carbohydrates  in  proportion  to  the  protein. 
Oat  straw  has  a  wide  ratio,  namely  1 :  33.7.  The  corn  ratio 
is  medium,  while  the  ratio  of  oil  meal,  1 :  1.7,  is  called  narrow. 

The  Wolff-Lehiriann  feeding  standards  for  farm  animals 
are  the  oldest  and  most  used.  They  were  constructed  after 
many  scientific  and  practical  experiments  on  domestic 


THE  ANIMAL  AND   ITS  FEED 


265 


animals  had  been  made  to  determine  the  proper  amounts  of 
protein,  fat,  and  carbohydrates  for  a  ration.  The  results 
of  this  work  are  embodied  in  what  are  commonly  called  feed- 
ing standards.  A  ration  conforming  to  such  a  standard, 
i.e.  one  containing  the  proper  amounts  of  digestible  pro- 
tein, fat,  and  carbohydrates,  is  called  a  balanced  ration. 
Feeding  standards  are  not  hard  and  fast  rules,  because  there  are 
differences  in  feeds  and  animals ;  but  they  are  good  general 
guides.  Below  are  examples  of  standard  rations  for  several 
animals.  For  complete  tables,  texts  on  feeds  and  feeding 
should  be  consulted. 

WOLFF-LEHMANN  STANDARD 
FOR  1000  LB.  LIVE  WEIGHT,  DAILY 


DIGESTIBLE 

DRY 

NUTRITIVE 

SUB. 

RATIO 

Prot. 

Garb. 

Fat 

Ib. 

Ib. 

Ib. 

Ib. 

Cow,  milk  yield  22  Ib.     . 

29 

2.5 

13 

0.5 

1:5.7 

Fattening  steer,  1st  period 

30 

2.5 

15 

0.5 

1:6.5 

Horse,  medium  work  .     . 

24 

2.0 

11 

0.6 

1:6.2 

This  table  indicates  that  a  cow  yielding  22  pounds  of  milk 
of  average  composition  will  need  daily  29  pounds  of  dry 
matter,  which  shall  contain  2.5  pounds  of  digestible  protein, 
13  pounds  of  carbohydrates,  and  0.5  pound  of  fat,  for  every 
1000  pounds  of  her  live  weight. 

Practical  tests  have  shown  that  animals  generally  thrive 
better  when  the  ration  is  properly  balanced.  A  balanced  ration 
is  more  economical  for  the  farmer  as  well  as  better  for  the 
animal.  There  is  generally  waste  in  an  unbalanced  ration. 
If,  for  instance,  an  animal  is  fed  a  ration  which  is  too  high  in 


266  CHEMISTRY  AND   DAILY  LIFE 

carbohydrates  and  too  low  in  protein,  it  will  consume  more 
carbohydrates  than  it  needs  in  order  to  get  the  necessary 
protein.  Sometimes,  under  special  conditions,  depending 
on  the  feed  on  hand  and  the  market  value,  it  is  necessary  or 
desirable  to  feed  an  unbalanced  ration.  This  should,  how- 
ever, be  guarded  against  as  far  as  possible. 

Young  animals  require  less  food  than  older  ones,  to  produce 
the  same  increase  in  their  weight.  Thus  it  is  more  profitable 
to  fatten  a  pig  which  is  less  than  a  year  old  than  one  nearly  two 
years  old.  Growing  animals  need  an  abundance  of  protein 
and  ash  in  their  rations.  Narrow  rations  suit  them  best. 
Milk  is  a  narrow  ration,  and  it  is  well  adapted  for  young 
growing  animals.  The  food  requirements  of  fattening  animals 
are  quite  different  from  this.  When  fattening,  an  animal  is 
not  storing  up  protein,  consequently  its  demands  for  protein 
are  much  less  than  in  the  case  of  a  growing  animal.  In  fact, 
carbohydrates  and  fats  can  be  abundant  in  the  rations  of  fat- 
tening animals,  and  a  nutritive  ration  of  1 :  10  has  actually 
been  found  satisfactory.  This  is  much  wider  than  that  rec- 
ommended by  the  Wolff-Lehmann  standard,  but  it  is  now 
considered  as  sound  practice  by  the  best  authorities. 

Working  animals  may  also  advantageously  be  fed  rations 
of  fairly  wide  nutritive  ratios.  Both  heat  and  other  energy 
can  be  produced  by  animals  from  carbohydrates  and  fats, 
as  already  stated.  Since  this  is  true,  no  large  supply  of 
protein  above  that  required  for  maintenance  need  be  supplied. 
The  farmer  always  produces  an  abundance  of  carbohydrates, 
and  for  this  reason  it  is  fortunate  that  working  and  fattening 
animals  as  well  can  be  properly  fed  with  the  farm-grown 
materials,  without  the  purchase  of  protein  concentrates,  such 
as  gluten  feed,  bran,  or  oil  meal.  Horses  working  on  the 
sugar  plantations  of  the  Fiji  Islands  receive  15  pounds  of 
molasses  daily,  and  their  feed  has  a  nutritive  ratio  of  1 :  11.8. 


THE  ANIMAL  AND  ITS  FEED  267 

It  is  said  that  they  do  well  on  this  ration.  Milch  cows  are 
machines  producing  an  abundant  secretion  of  a  highly  nitrog- 
enous character,  for  30  pounds  of  milk  contain  one  pound 
of  protein.  For  this  reason,  it  is  clear  that  their  ration 
should  be  richer  in  protein  than  that  of  a  work  horse  or  fat- 
tening steer.  It  is  conceded  that  cows  need  at  least  0.6  pound 
of  protein  to  repair  the  daily  wear  and  tear  of  their  cells.  This, 
plus  what  goes  into  the  milk,  makes  1.6  pounds.  Practice  has 
established  that  an  additional  supply  of  protein,  over  that 
required  merely  for  maintenance  and  for  the  milk,  is  neces- 
sary. For  milch  cows  a  nutritive  ratio  of  1 :  5.5  to  1 :  7.0  is  the 
general  practice  and  gives  the  best  results.  Young  pasture 
grass,  as  good  a  milk  producer  as  we  have,  is  even  narrower 
than  this.  All  farm  animals  required  to  work,  fatten,  or 
produce  milk  must  receive  grain  or  concentrated  food  as  a 
part  of  their  ration.  Bulky,  coarse  food,  such  as  the  hays, 
use  much  energy  in  being  moved  along  the  intestinal  tract 
and  will  not  give  the  best  results  when  used  alone. 

QUESTIONS 

1.  Of  what  is  an  animal  composed  ?     How  much  water  is  there 
in  a  1000-pound  horse  ? 

2.  Of  what  use  is  ash  or  mineral  matter  in  food  ? 

3.  What  does'  an  animal  do  with  the  starch  and  sugar  it  eats  ? 
What  with  the  protein  ?    What  with  the  fat  ? 

4.  What  is  meant  by  " digesting"  the  food,  and  what  is  the 
name  given  to  the  substances  that  do  this  work  ? 

5.  Describe  digestion  in  the  mouth  and  in  the  stomach. 

6.  What  curdles  the  milk  in  the  stomach  ?    Is  this  the  same  sub- 
stance used  in  cheese  making  ? 

.    7.   What  happens  to  the  food  in  the  intestine  ? 

8.   What  is  the  purpose  of  respiration,  and  why  should  we  live 
in  well-ventilated  rooms  ? 


268  CHEMISTRY  AND   DAILY  LIFE 

9.    Do  foods  differ  in  digestibility?     What  foods  leave  large 
residues  in  the  intestine  ? 

10.  What  is  meant  by  the  nutritive  ratio  of  a  feed  ? 

11.  From  the  tables  in  a  text  on  feeds  and  feeding,  calculate  the 
nutritive  ratio  of  the  oat  grain  and  alfalfa  hay ;  also  of  milk. 

12.  From  the  same  tables,  calculate  a  balanced  ration  for  a  dairy 
cow  weighing  1000  pounds  and  giving  30  pounds  of  milk  daily. 
The  materials  available  are  oats,  corn,  gluten  feed,  and  alfalfa  hay. 

13.  What  differences  may  there  be  in  the  ration  of  a  fattening 
pig,  a  working  horse,  and  a  growing  animal  ? 


CHAPTER   XIX 
HUMAN   AND   ANIMAL   FOODS 

THE  foods  consumed  by  human  beings  are  of  vegetable  and 
animal  origin.  The  vegetable  kingdom  furnishes  all  of  the 
necessary  constituents  of  food  in  cheaper  form  than  the  meat 
of  animals  and  without  an  excess  of  protein.  The  distin- 
guishing characteristic  of  vegetable  foods  is  their  richness  in 
carbohydrates,  a  feature  which  offers  a  striking  contrast  to 
animal  flesh,  which  contains  practically  no  carbohydrates.  The 
only  common  food  of  animal  origin  containing  a  fair  propor- 
tion of  carbohydrates  is  milk  with  its  content  of  milk  sugar. 
The  disadvantage  of  vegetable  foods  is  that  they  are  relatively 
bulky  and  as  a  rule  but  incompletely  digested,  for  their  chief 
nutrient,  starch,  is  contained  in  a  vast  number  of  cells  the 
walls  of  which  are  composed  of  cellulose,  which,  as  already 
pointed  out,  is  not  easily  dissolved  by  the  digestive  juices. 
It  is  strongly  in  favor  of  vegetable  foods,  however,  that  they  con- 
tain all  of  the  various  essential  food  constituents,  and  that  in 
many  vegetables  these  are  present  in  well-balanced  proportion. 
Bulkiness  is  a  property  that  is  common  to  all  vegetable 
foods.  It  is  due  chiefly  to  the  large  amounts  of  water  and 
carbohydrates  which  vegetable  matter  contains.  The  green 
fresh  vegetables  are  especially  bulky ;  in  fact,  their  bulk  is 
out  of  all  proportion  to  the  small  amount  of  nutrients  which 
they  contain.  Four-fifths  of  the  weight  of  fruits,  green 
peas,  beans,  cabbage,  carrots,  radishes,  etc.,  is  due  to  water. 
It  is  probably  safe  to  conclude,  however,  that  the  proteins. 

269 


270  CHEMISTRY  AND  DAILY  LIFE 

fats,  and  carbohydrates  in  vegetables  are  equal  in  nutritive  value 
to  the  same  substances  derived  from  the  animal  kingdom. 

Bread  is  made  from  the  grains  of  cereals.  It  is  the  basis 
of  human  nutrition — the  staff  of  life.  Cereals  also  enter 
largely  into  the  rations  of  our  domestic  animals.  The  im- 
portance of  cereals  rests  on  the  fact  that  they  and  the  products 
made  from  them  furnish  the  chief  food  constituents  —  pro- 
teins, carbohydrates,  fats,  and  mineral  matter  —  cheaply, 
abundantly,  and  in  an  agreeable  form.  These  qualities 
distinguish  the  cereals  as  foodstuffs  of  the  first  rank.  Never- 
theless, when  used  alone,  they  are  not  well  suited  for  the 
production  of  growth,  and  should  consequently  be  accom- 
panied by  foods  richer  in  protein,  like  milk  or  eggs.  In  the 
case  of  domestic  animals,  mill  concentrates  like  gluten  feeds 
and  oil  meals  will  serve  to  furnish  the  additional  protein 
required.  The  carbohydrates  predominate  in  some  cereals, 
like  rice  and  Indian  corn  (maize) ,  and  these  are  consequently 
prominent  as  sources  of  energy.  Rice  and  wheat  have  a 
loiv  fat  content,  while  the  oat  and  corn  grain  contain  as  high 
as  5  per  cent  of  fat.  Though  the  proportion  of  protein  in 
cereals  varies,  yet  the  protein  is  extremely  useful,  for  it  fur- 
nishes the  materials  necessary  for  the  growth  and  repair  of 
tissue.  Wheat  is  the  most  important  cereal,  but  rye,  rice,  corn, 
oats,  barley,  and  buckwheat  are  also  of  great  value.  The  sticky 
character  of  the  proteins  of  wheat  peculiarly  adapts  it  to  the 
making  of  light,  porous  bread.  This  same  property  is  also 
possessed  by  the  proteins  of  rye,  but  none  of  the  other  cereals 
will  make  a  light,  porous  loaf  of  bread.  Barley  is  one  of  the 
most  ancient  of  foods.  It  was  highly  esteemed  by  the 
athletes  of  ancient  Greece.  The  amount  of  water  in  cereals 
varies  but  slightly  and  averages  about  11  per  cent.  The 
general  composition  of  the  cereals  is  about  as  follows : 
water,  11  per  cent ;  protein,  10  to  12  per  cent ;  carbohydrates, 


HUMAN  AND  ANIMAL   FOODS  271 

65  to  70  per  cent ;  fat,  0.5  to  8  per  cent ;  ash,  2  per  cent.  Such 
averages  are  useful,  but  they  should  not  be  applied  too  rigidly 
to  any  particular  sample  of  grain.  Thus  the  proteins  of 
wheat  may  run  as  high  as  17  per  cent,  or  as  low  as  8.5  per 
cent,  depending  upon  the  climate  in  which  the  wheat  was 
grown ;  but  these  figures  are  extreme  and  unusual.  Most 
of  the  cereals  contain  only  from  2  to  3  per  cent  of  cellulose ; 
but  grains  having  thick  outer  coats,  like  oats  and  buckwheat, 
have  a  cellulose  content  of  10  to  12  per  cent. 

Before  being  used  for  human  food,  the  cereals  are  usually 
ground  to  a  powder.  From  this  powder  the  coarser  cellulose 
particles  are  sifted  out,  and  the  fine  product  so  obtained  is 
called  flour,  the  term  meal  being  applied  to  the  coarser 
products.  In  thus  sifting  out  the  bran,  i.e.  the  outer  coating 
of  the  grain  in  the  case  of  wheat,  the  quantity  of  mineral 
matter  in  the  flour  is  greatly  reduced.  For  children  it  would 
be  better  if  their  bread  were  made  from  the  coarser  meal,  because 
the  cellulose  and  mineral  matter  contained  in  it  are  laxative 
in  their  action.  Twenty-five  years  ago  the  wheat  was  simply 
crushed  and  ground  between  millstones,  and  then  crudely 
separated  into  three  products  by  sifting.  These  three 
products  were  called  bran,  flour,  and  middlings.  Bran,  which 
is  so  commonly  fed  to  dairy  cows  to-day,  is  rich  in  mineral 
matter,  especially  in  potassium  and  phosphorus,  but  it  also 
contains  about  15  per  cent  of  protein.  All  of  these  have  been 
taken  from  the  wheat  kernel. 

Foods  are  prepared  for  the  table  by  baking  and  cooking, 
during  which  processes  they  are  acted  upon  physically, 
chemically,  and  bacteriologically.  The  chemical  compounds 
of  which  foods  are  composed  are  altered  to  a  greater  or  lesser 
degree  by  heat.  In  boiling  a  potato,  for  instance,  the  cellulose 
of  the  cell  walls  unites  to  a  certain  extent  with  water ;  that 
is,  it  is  partly  hydrated,  and  so  becomes  softened.  Further- 


272  CHEMISTRY  AND   DAILY  LIFE 

more,  at  the  temperature  of  boiling  water,  starch  is  slightly 
changed  to  dextrin ;  but  the  change  is  only  slight,  because 
the  temperature  is  not  high  enough  to  effect  complete  alter- 
ation. On  the  other  hand  when  baked  with  a  dry  heat,  more 
of  the  starch  will  be  dextrinized,  for  the  temperature  of  the 
oven  is  considerably  above  that  of  boiling  water.  The 
sugars  are  not  altered  appreciably  by  boiling  water,  but  by 
dry  heat  they  may  be  changed  to  a  dark  brown  substance 
called  caramel.  During  the  formation  of  caramel,  water  is 
given  off.  The  dark  color  of  the  crust  of  the  loaf  of  bread  is 
due  to  caramel.  The  fats  are  acted  upon  to  some  extent  by 
heat.  Some  of  the  vegetable  oils  undergo  slight  oxidation, 
but  these  changes  are  not  regarded  as  of  any  great  influence 
on  the  food  value  of  these  substances.  In  general,  the  pro- 
teins tend  to  become  less  soluble  by  the  action  of  heat,  but 
not  all  proteins  are  thus  altered.  The  white  of  the  egg  is 
coagulated  by  heat,  but  the  main  protein  of  corn  meal  is  not. 
Coagulated  or  hardened  protein  will  be  digested  more  slowly 
than  raw  protein.  But  cooking  produces  such  important 
physical  changes,  especially  on  starch  and  the  cell  wall,  that 
its  good  effects  more  than  counterbalance  the  unfavorable 
action  on  the  proteins. 

The  physical  changes  produced  by  heat  and  water  consist 
of  a  partial  disintegration  of  the  animal  and  vegetable  tissues  of 
foods.  The  cementing  materials  are  loosened,  and  a  softening 
of  the  tissues  results.  Often  the  action  proceeds  still  farther 
in  the  case  of  vegetable  foods,  resulting  in  the  disintegration 
of  the  individual  starch  granules.  When  foods  are  subjected 
to  dry  heat,  their  moisture  is  converted  into  steam,  which 
causes  the  bursting  of  the  cells.  Popping  corn  is  a  good 
illustration  of  this.  In  baking  bread  or  other  cereal  doughs, 
the  starch  grains  are  partially  ruptured,  and  they  are  conse- 
quently more  readily  digested  than  when  raw.  Prolonged 


HUMAN  AND   ANIMAL  FOODS 


273 


and  slow  heat  is  most  effective  in  improving  the  mechanical 
condition  of  the  tissues.  At  too  high  a  temperature,  the 
natural  flavoring  materials  in  the  foods  are  partly  volatilized, 
and  so,  of  course,  lost.  By  boiling  foods  in  water,  salts  are 


FIG.  91.  —  (A)  Popcorn  partly  popped.     (B)  Popcorn  fully  popped. 
Highly  magnified. 

extracted  from  them,  and  so  their  palatability  is  lowered. 
This  undesirable  effect  will  be  greatly  lessened  by  adding  salt 
to  the  water  in  proper  quantity. 

The  bacterial  organisms  in  foods  are  destroyed  in  the  pro- 
cess of  cooking,  provided  a  temperature  of  150°  F.  is  reached 
and  maintained  for  several  minutes.  The  interior  parts 
of  foods  rarely  reach  a  temperature  above  200°  F.  while 
cooking  goes  on.  Not  only  are  bacteria  destroyed  by  cooking 
or  baking,  but  various  parasites,  such  as  trichina  and  tapeworms, 
are  also  destroyed.  But  it  should  be  remembered  that  cooked 
foods  are  easily  reinoculated ;  in  some  cases  more  readly 
than  fresh  foods,  because  they  are  in  a  more  disintegrated 
condition.  In  many  instances,  bacteria  and  yeasts  are  of 
material  assistance  in  the  preparation  of  food,  as  in  bread 
making,  butter  making,  and  the  curing  of  cheese;  and  it  must 


274  CHEMISTRY  AND   DAILY  LIFE 

be  borne  in  mind  that  in  such  cases  the  bacteria  are  appar- 
,  ently  not  at  all  harmful  when  eaten  with  the  raw  food. 

In  order  to  make  flour  available  as  food  it  must  be  cooked 
in  a  proper  manner,.  The  simplest  way  is  to  mix  it  with 
water  and  bake  it.  This  is  ship's  biscuit,  a  leaden,  heavy 
mass.  Bread  may  be  made  light  by  having  a  gas,  carbon  dioxide, 
develop  in  the  mass,  which  slowly  pushes  the  particles  apart  and 
thus  produces  a  light  sponge.  The  viscid  nature  of  the  gluten 
of  the  flour  allows  this  to  be  done  successfully.  To  produce 
this  gas,  yeast  is  commonly  used.  It  consists  of  very  minute 
plants,  capable  of  breaking  up  sugar  into  carbon  dioxide 
and  alcohol.  The  carbon  dioxide  gas  is  the  effective  agent 
in  lightening  the  dough.  Two-thirds  of  the  bulk  of  the  fer- 
mented bread  is  gas.  Of  the  solid  residue,  about  40  per  cent  is 
water.  This  is  relatively  much  less  than  the  water  content 
of  meat,  which  is  from  70  to  80  per  cent.  Bread  also  con- 
tains a  little  more  than  50  per  cent  of  carbohydrates,  about 
7  to  8  per  cent  of  proteins,  and  2  to  3  per  cent  of  fat  and  ash. 

All  baking  powders  contain  at  least  two  ingredients,  (1)  a 
carbonate,  and  (2)  a  compound  which  serves  to  liberate  the 
carbon  dioxide  gas.  The  carbonate  from  which  the  gas  is 
obtained  is  almost  always  sodium  bicarbonate,  NaHC03, 
commonly  known  as  "  baking  soda  "  or  "  saleratus."  The 
compounds  that  serve  to  decompose  the  baking  soda  are  in 
general  acidic  in  character,  those  in  common  use  being 
cream  of  tartar,  KHC4H4O6,  tartaric  acid,  H2C4H4O6,  calcium 
acid  phosphate,  CaH4(PO4)2,  and  alum,  NH4A1(SO4)2.  These 
may  be  used  separately  or  in  combination.  All  of  these 
liberate  carbon  dioxide  when  mixed  with  baking  soda  and  mois- 
tened, but  the  products  left  in  the  food  differ  widely  in  amount 
and  character.  It  is  the  nature  and  amount  of  the  residue 
that  remains  in  the  bread  which  determines  whether  one 
baking  powder  is  more  desirable  than  another.  In  the  cream 


HUMAN  AND  ANIMAL  FOODS  275 

of  tartar  baking  powder,  the  acid  ingredient  is  potassium  acid 
tartrate.  This  reacts  with  the  sodium  bicarbonate,  liber- 
ating carbon  dioxide  and  forming  sodium  potassium  tartrate, 
which  remains  in  the  bread.  In  the  phosphate  baking  pow- 
der the  acid  constituent  is  monocalcium  phosphate  and 
the  residue  left  in  the  bread  is  a  sodium  calcium  phosphate. 
The  residues  left  in  the  bread  or  other  foodstuffs  from  these 
two  powders  are  perfectly  harmless.  In  the  alum  baking 
powders  the  active  agent  which  decomposes  the  baking  soda 
is  ammonium  aluminum  sulphate,  although  sometimes  po- 
tassium or  sodium  aluminum  sulphate  is  used..  In  any  case, 
the  aluminum  hydrate  formed  in  the  reaction  with  the 
sodium  bicarbonate  is  a  harmful  material  which  forms 
aluminum  chloride  with  the  hydrochloric  acid  in  the 
stomach,  and  this  salt  hinders  digestion  in  the  same  way 
that  alum  does : 

2  NH4A1(SO4)2  +  6  NaHCOs 

alum  "soda" 

=  2  A1(OH)3  +  3  Na2S04  +  (NH4)2SO4  +  6  CO2 

aluminum  sodium  ammonium  carbon 

hydrate  sulphate  sulphate  dioxide 

In  many  states  the  sale  of  alum  baking  powders  is  prohibited 
by  law.  All  baking  powders  contain  starch  as  a  filler.  From 
what  has  been  said  it  is  clear  that  baking  powder  is  a  chemical 
preparation  which  when  brought  in  contact  with  water  liberates 
carbon  dioxide.  The  result  of  the  action  is  similar  to  that  of 
yeast,  only  much  more  rapid. 

Indian  corn  forms  a  considerable  part  of  the  food  of  all  of  the 
people  of  the  United  States.  In  the  south  corn  bread  is  the 
only  bread  ever  tasted  by  thousands.  Corn  is  also  used  exten- 
sively as  a  source  of  corn  starch,  from  which  corn  sirup  is  made 
by  boiling  the  starch  with  dilute  sulphuric  acid.  After  sep- 
arating the  starch  from  the  grain,  the  residue  is  sold  as  a  high 


276  CHEMISTRY  AND  DAILY  LIFE 

protein  stock  feed  under  the  name  of  gluten  feed.  It  con- 
tains from  24  to  28  per  cent  protein.  Barley  is  chiefly  used 
as  a  human  food  in  the  form  of  either  pearl  or  patent  barley. 
The  former  consists  of  the  whole  grain  which  has  been  pol- 
ished after  removal  of  the  husk.  The  patent  barley  is  simply 
pearl  barley  ground  to  a  flour.  Barley  is  extensively  used  in 
the  brewing  of  malt  liquors.  In  brewing,  the  seed  is  first 
allowed  to  sprout ;  thus  starch  is  changed  to  sugars  through 
the  action  of  diastase,  a  ferment  which  occurs  in  germinating 
seeds.  In  turn  the  sugars  are  broken  by  yeasts  into  carbon 
dioxide  and  alcohol.  The  alcohol  is  the  constituent  wanted 
in  these  liquors.  The  residues  from  the  brewing  and  distil- 
ling industries  are  dried.  They  are  rich  protein  cattle  foods, 
such  as  brewers'  grains  and  distillers'  grains,  having  a  content 
of  25  to  30  per  cent  of  protein.  "  Ajax  "  is  such  dried  dis- 
tillers' grain.  The  cereal  grain  rice  is  extremely  rich  in 
carbohydrates,  and  the  common  product  on  the  market  has 
been  prepared  by  polishing  the  original  seed.  This  polishing 
process  was  formerly  carried  out  by  rotating  the  seeds  in 
drums  lined  with  sheepskin,  but  is  now  done  by  agitating  the 
grains  with  talc. 

In  preparing  breakfast  foods,  the  entire  clean  grain  is 
ground  or  pulverized  in  some  cases,  while  in  others  the  bran 
and  germ  are  first  removed.  In  order  to  improve  their  keep- 
ing qualities,  these  foods  are  often  sterilized  before  being  put 
up  in  sealed  packages.  "  Shredded  wheat  "  is  a  preparation 
of  whole  wheat,  which  has  been  cooked,  then  shredded,  and 
finally  baked.  "  Force  "  is  malted  whole  wheat  in  the  form 
of  flakes,  cooked  with  steam.  By  malting  or  partly  pre- 
digesting  the  starch,  a  part  of  the  latter  is  made  soluble. 
"  Grapenuts  "  is  another  malted  preparation  of  the  entire 
wheat  berry.  The  process  of  malting  has  changed  some  of 
the  starch  to  sugar  which  gives  the  food  its  sweet  taste. 


HUMAN  AND  ANIMAL  FOODS  277 

Oatmeal  is  the  whole  oat  with  the  outer  husk  removed. 
This  reduces  the  cellulose  content  very  materially.  Corn 
flakes  consist  of  cooked  corn,  which  has  been  treated  with 
malt  honey,  dried,  rolled,  and  baked.  When  the  amount  of 
food  which  a  package  of  breakfast  food  contains  is  compared 
tcith  its  cost,  the  material  is  found  to  be  quite  expensive.  The 
cereals  had  better  be  bought  in  proper  form  and  cooked  at 
home. 

The  pulses  include  beans,  peas,  and  lentils.  The  character- 
istic of  these  leguminous  foods  is  their  richness  in  protein. 
When  their  nutritive  value  is  compared  with  their  price,  they 
are  undoubtedly  the  cheapest  of  all  foods,  and  on  this  account 
they  may  well  be  called  the  "  poor  man's  beef."  In  an  air- 
dried  condition,  they  contain  about  10  per  cent  of  water, 
20  to  25  per  cent  of  protein,  60  per  cent  of  carbohydrates, 
1  to  2  per  cent  of  fat,  and  3  to  5  per  cent  of  ash.  The  pulses 
are  well  supplied  with  carbohydrates,  but  they  are  poor  in 
fat.  The  peanut,  although  botanically  one  of  the  pulses, 
really  resembles  the  true  nuts  in  composition,  and  like  them 
it  'is  rich  in  protein  and  fat. 

Just  as  the  larger  portion  of  the  grain  of  cereals  is  really  a 
storehouse  of  nutrients  for  the  use  of  the  young  plant,  so 
roots  and  tubers  may  be  regarded  as  reserves  for  the  nourish- 
ment for  the  adult  plant  itself.  During  the  prosperous  days 
of  spring  and  summer  the  plant  lays  by  a  goodly  supply  of 
food  material  for  the  seed  production  of  the  late  autumn  or  the 
next  spring.  The  potato  is  one  of  the  standard  vegetables, 
chiefly  valued  because  of  its  richness  in  starch.  There  are 
produced  in  the  United  States  annually  about  300,000,000 
bushels  of  potatoes.  A  fresh  potato  contains  82  per  cent  of 
water,  16  per  cent  of  starch,  and  but  0.3  per  cent  of  protein. 
The  rest  is  ash  and  fat.  From  this  it  is  clear  that  the  potato 
is  one-sided  in  composition  and  not  like  the  pulses  or  the 


278  CHEMISTRY  AND   DAILY  LIFE 

cereals.  A  boiled  potato  contains  less  water  than  a  fresh 
one,  the  content  being  about  75  per  cent  of  water  and  20 
per  cent  of  starch.  There  is  some  loss  of  material  in  boiling, 
but  this  loss  consists  mainly  of  mineral  matter  and  proteins, 
and  it  is  consequently  slight. 

The  turnip  is  a  vegetable  of  but  slight  nutritive  value.  It 
contains  about  90  per  cent  of  water  and  5  to  8  per  cent  of  car- 
bohydrates. Its  water  content  is  therefore  even  greater  than 
that  in  milk.  None  of  this  carbohydrate  material  is  starch ; 
it  is  present  in  the  form  of  pectins.  The  peculiar  flavor  of 
turnips  which  is  so  highly  esteemed  by  some  persons  is  due  to 
complex  sulphur  compounds.  Carrots  are  decidedly  more  nu- 
tritious than  turnips,  mainly  because  of  their  richness  in 
sugar,  of  which  they  contain  nearly  10  per  cent.  On  boiling 
carrots,  about  25  per  cent  of  this  sugar  is  lost.  Cabbage 
is  a  favorite  vegetable  with  many  people,  especially  those  of 
the  German  race.  It  is  also  prized  by  good  shepherds  as 
a  sheep  feed.  Cabbage  contains  90  per  cent  of  water,  2  per 
cent  of  protein,  and  6  per  cent  of  carbohydrates. 

A  distinguishing  feature  of  roots  and  tubers  is  that  they  are 
rich  in  ash,  especially  in  salts  of  potassium  and  calcium. 
This  gives  them  greater  value  in  diets  and  animal  rations 
than  they  would  otherwise  deserve.  The  rutabaga,  radish, 
onion,  and  kohl-rabi  have  compositions  that  are  very  similar 
to  that  of  the  cabbage.  Beet  roots  are  richer  in  sugar,  con- 
taining from  10  to  12  per  cent  of  readily  available  carbohy- 
drates. The  sugar  beet  is  one  of  the  main  sources  of  our 
table  sugar ;  it  contains  from  10  to  20  per  cent  of  sucrose, 
cane  sugar. 

When  judged  strictly  from  a  chemical  standpoint,  fruits 
would  seem  to  be  of  little  value  as  food,  owing  to  their  low 
content  of  the  ordinary  food  constituents ;  but  when  the 
delight  which  they  afford  to  the  palate  and  the  eagerness 


HUMAN  AND  ANIMAL  FOODS  279 

with  which  they  are  eaten  by  normal  children  are  considered, 
fruits  certainly  appear  to  be  a  very  important  human  food. 
Fresh  fruit  in  general  contains  about  85  per  cent  to  95  per 
cent  of  water,  0.5  per  cent  of  protein,  0.5  per  cent  of  fat,  and 
5  to  10  per  cent  of  carbohydrates  ;  also  a  small  amount  of  ash 
and  some  organic  acids.  Calculated  on  the  amount  of  dry 
matter,  the  quantity  of  ash  in  fruits  is  really  considerable.  The 
value  of  fruits  as  food  depends  largely  on  their  mineral  con- 
tent and  their  flavor.  The  ash  of  fruits  is  rich  in  potassium, 
calcium,  and  iron  salts,  all  of  which  are  valuable  to  the  animal 
cell.  One-half  of  the  carbohydrate  content  of  fruits  usually 
consists  of  fructose,  fruit  sugar.  In  apples,  apricots,  and 
pineapples,  on  the  other  hand,  cane  sugar  is  present. 

The  process  of  canning  fruit  is  only  about  one  hundred  years 
old.  It  was  first  used  by  a  Frenchman  named  Appert,  who 
put  fruit  into  cans  or  bottles  which  he  sealed.  He  then 
placed  the  full  cans  or  bottles  in  water  and  boiled  them  for 
some  time.  In  Appert's  time,  and  indeed  until  recent  years, 
it  was  generally  thought  that  the  oxygen  of  the  air  caused 
the  spoiling  or  decomposition  of  the  food.  To  exclude  the 
air  from  the  cans  was  the  explanation  of  success  in  canning 
in  his  time.  It  is  now  known  that  it  is  not  the  oxygen  of  the 
air  which  causes  canned  fruit  and  vegetables  to  spoil,  but  rather 
the  bacteria  and  other  microscopic  organisms  that  are  present. 
Appert's  theory  was  wrong,  but  his  method  of  sealing  and 
cooking  by  which  he  really  sterilized  the  contents  of  the  cans 
was  correct.  If  food  is  sterilized  perfectly,  and  the  opening 
of  the  jar  is  then  plugged  with  sterile  cotton,  the  contents 
will  not  ferment ;  for  the  bacteria  and  yeasts  to  which  such 
changes  are  due  cannot  pass  through  the  cotton. 

Bacteria  and  yeasts  are  in  the  air,  in  the  soil,  and  on  all 
vegetable  matter.  In  fact  they  are  of  almost  universal  occur- 
rence. Some  of  them  do  great  harm  ;  but  it  is  believed  that 


280  CHEMISTRY  AND  DAILY  LIFE 

most  of  them  are  beneficial.  Fruits  spoil  because  of  the  devel- 
opment of  these  microorganisms,  which  bring  about  chemical 
changes  in  the  tissues,  as  the  disagreeable  odors  and  flavors 
that  are  produced  clearly  indicate.  Bacteria  grow  luxuriantly 
in  foods  that  are  rich  in  nitrogenous  material,  especially  if  the 
foods  are  warm  and  moist.  Among  such  foods  are  meat, 
fish,  eggs,  peas,  beans,  and  milk.  All  of  these  are  difficult 
to  preserve  because  of  the  ever  present  bacteria.  Thus  it 
is  that  in  warm,  muggy  weather  fresh  meat,  fish,  milk,  etc.,  spoil 
quickly.  Bacteria  do  not  develop  in  material  containing 
large  amounts  of  sugar ;  but  when  small  quantities  of  sugar 
are  present,  both  yeasts  and  bacteria  grow  readily.  Fruits 
are  usually  slightly  acid,  and  so  in  general  they  do  not  sup- 
port bacterial  growth.  It  is  for  this  reason  that  canned  fruits 
are  more  commonly  fermented  by  yeasts  than  by  bacteria. 
Some  vegetable  foods  contain  so  much  acid  and  so  little 
nitrogenous  material  that  very  few  bacteria  or  yeasts  will 
attack  them.  Lemons,  cranberries,  and  rhubarb  belong  to 
this  class. 

The  proper  use  of  higher  temperatures  is  by  far  the  best  way 
of  checking  the  growth  of  microorganisms,  for  most  of  them 
are  destroyed  if  exposed  for  ten  or  fifteen  minutes  to  the  tem- 
perature of  boiling  water,  i.e.  100°  C.  or  212°  F.  But  if  the 
bacteria  produce  spores,  boiling  must  be  continued  for  an  hour 
or  more  to  insure  their  complete  destruction.  Yeasts  and  their 
spores  are  more  easily  destroyed  than  bacterial  spores.  Of 
course,  one  generally  does  not  know  what  kinds  of  organisms 
are  present  in  the  particular  food  that  is  to  be  canned,  but  it 
is  well  known  that  most  fruits  are  acidic  and  do  not  favor  the 
growth  of  bacteria,  and  that  as  a  rule  the  yeasts  can  be 
destroyed  by  heating  from  10  to  15  minutes  at  a  temperature 
of  212°  F.  //  no  living  organisms  or  spores  are  left,  and  the 
sterilization  of  all  the  dishes  and  appliances  used  has  been 


HUMAN  AND  ANIMAL  FOODS  281 

i 
thorough,  there  is  no  reason  why  the  fruit,  if  properly  sealed, 

should  not  keep  for  a  year  or  longer.  When  fruit  is  preserved 
with  a  large  amount  of  sugar  (a  pound  of  sugar  to  a  pound 
of  fruit),  it  does  not  need  to  be  hermetically  sealed  to  protect 
it  from  yeasts  or  bacteria,  because  the  thick  sirup  formed  is 
not  favorable  to  their  growth.  Molds,  however,  will  grow 
on  fruit  when  thus  preserved,  and  it  is  better  to  seal  the  jars 
in  any  case. 

Every  housewife  is  familiar  with  molds,  which  under  favor- 
able conditions  of  moisture  and  warmth  grow  upon  almost 
any  kind  of  organic  material.  For  example,  in  damp,  warm 
weather  molds  form  in  a  short  time  on  all  sorts  of  starchy  foods, 
such  as  boiled  potatoes,  breads,  mush,  etc.,  as  well  as  on  canned 
and  preserved  fruits.  Molds  develop  from  spores  which  are 
always  floating  about  in  the  air.  When  a  spore  falls  upon  a 
substance  containing  moisture  and  suitable  food,  it  sends  out 
fine  threads,  which  branch  and  work  their  way  over  and  into 
the  attacked  substance.  If  one  of  these  spores  drops  on  a 
jar  of  preserves  or  a  tumbler  of  jelly,  it  will  germinate,  if 
there  is  moisture  enough  present  and  the  temperature  is 
favorable.  Molds  do  not  penetrate  deeply  into  solid  foods, 
or  into  liquids  or  semiliquids,  because  they  require  free  oxygen 
for  growth;  but  if  given  time,  they  will  at  ordinary  room 
temperature  gradually  penetrate  solid  substances  which  con- 
tain moisture.  For  these  reasons  they  will  not  cause  the 
ordinary  fermentation  of  canned  fruit.  To  kill  mold  spores, 
food  must  be  exposed  to  a  temperature  of  from  150°  F.  to  21%? 
F.,  after  which  it  should  be  kept  in  a  cool,  dry  place  and  cov- 
ered carefully  so  that  no  floating  spores  can  find  lodgment  on 
its  surface. 

Dates,  figs,  prunes,  and  other  dried  fruits  generally  contain 
from  20  to  25  per  cent  of  water  and  65  per  cent  of  carbohy- 
drates ;  of  the  latter  a  large  part  is  sugar.  The  remainder 


282  CHEMISTRY  AND   DAILY  LIFE 

i 
of  these  fruits  is  made  up  of  ash,  fat,  and  protein.     They  are 

valuable  food  materials,  which  are  rich  in  alkali  salts,  and 
commonly  act  as  mild  laxatives. 

Nuts  are  among  the  most  concentrated  of  foods  and  therefore 
present  a  strong  contrast  to'  the  water-containing  fruits. 
Nuts  are  rich  in  oil,  carbohydrates,  and  proteins,  and  this  makes 
them  extremely  nutritious.  Bulk  for  bulk,  dry  nuts  are 
doubtless  among  the  most  nutritious  foods  in  existence. 
Their  general  composition  is  roughly  as  follows  :  water,  4  to 
5  per  cent ;  protein,  15  to  20  per  cent ;  fat,  50  to  60  per  cent ; 
carbohydrates,  9  to  12  per  cent ;  cellulose,  3  to  5  per  cent ; 
mineral  matter,  1  per  cent.  As  the  figures  show,  fatty  matter 
predominates  in  nuts;  and  no  other  vegetable  substances, 
unless  they  be  flaxseed,  cottonseed,  and  castor  beans,  are 
so  rich  in  fat  as  nuts.  Occasionally  substitutes  for  ordinary 
butter  are  made  from  the  expressed  fats  of  nuts,  as  for 
example  "  nut  butter  "  and  "  nuttolene." 

It  is  not  the  nutritive  value  of  coffee,  tea,  and  cocoa  that 
makes  these  beverages  so  important,  but  rather  the  peculiar 
stimulating  and  restorative  effects  which  they  produce.  All 
of  them  owe  their  peculiar  virtues  to  the  alkaloids  which 
they  contain  (see  Chapter  IX).  In  coffee  and  tea  the  effect 
of  the  alkaloid  is  more  striking ;  but  in  cocoa  it  is  masked  by 
the  heavy  nutritious  fats  and  carbohydrates  that  are  present. 
The  three  alkaloids,  caffeine,  theine,  and  theobromine,  con- 
tained in  coffee,  tea,  and  cocoa  respectively,  have  a  certain 
relation  to  one  another,  and  consequently  their  effects  are 
somewhat  similar.  The  amount  of  these  alkaloids  present 
is  not  large,  being  only  from  1  to  2  per  cent ;  but  like  certain 
other  medicines,  such  alkaloids  in  even  very  small  quantities 
readily  affect  the  nervous  system.  The  coffee  bean,  the  tea 
leaf,  and  the  cocoa  seed  all  come  from  plants  that  are  grown 
in  the  tropics.  Children  ought  not  to  drink  either  coffee 


HUMAN  AND   ANIMAL  FOODS 


283 


FIG.  92.  — A  coffee  plant  in  blossom. 

or  tea  because  of  their  stimulating  action ;  but  they  may  use 
cocoa,  for  it  is  rich  in  the  ordinary  nutrients. 

Spices,  such  as  pepper,  allspice,  nutmeg,  and  cinnamon,  are 
not  foods  in  the  strict  sense  of  the  word,  but  nevertheless  they  are 
essential  constituents  of  the  diet.  They  arouse  the  appetite 
and  promote  the  secretion  of  the  gastric  juice.  Their  active 
principles  and  flavors  depend  upon  the  presence  of  volatile 
oils.  These  oils  are  not  of  the  same  kind  as  the  oils  of  the 
ordinary  seeds  and  the  fats  of  meat,  but  they  are  other  com- 
plex compounds  which  are  volatile,  as  their  name  implies. 
Vinegar  is  a  condiment  in  which  the  active  principle  is  acetic 
acid.  Vinegar  is  made  by  allowing  the  expressed  juice  of 
apples  or  other  fruits  to  ferment.  In  this  process  the  sugars 


284  CHEMISTRY  AND  DAILY  LIFE 


FIG.  93. — A  tea  plantation. 

in  the  fruits  are  first  changed  to  alcohols  by  yeasts  and  so  the 
juice  becomes  hard  cider ;  the  alcohols  are  then  changed  to 
acetic  acid  by  bacteria.  These  changes  are  brought  about  at 
ordinary  temperatures,  but  they  proceed  more  rapidly  at 
90°-100°  F. 

The  foods  of  animal  origin  include  meat,  gelatin,  fish,  eggs, 
and  milk.  These  are  all  high  protein  materials.  Meat  is 
characterized  by  a  high  ash,  fat,  and  protein  content.  The 
amount  of  fat  in  meat  varies  greatly  with  the  condition  of  the 
slaughtered  animal.  Lean  sirloin  has  about  the  following 
composition  :  water,  71  per  cent ;  protein,  25  per  cent ;  fat, 
3  per  cent ;  ash,  1  to  2  per  cent.  A  fat  sirloin  may  contain  as 
much  as  30  per  cent  of  fat.  It  should  again  be  recalled  that 
there  are  no  carbohydrates  in  meat.  Only  fresh  liver  and  oys- 
ters contain  the  animal  starch  called  glycogen,  and  even  this 
is  present  only  in  small  quantities.  A  piece  of  boiled  meat 
can  easily  be  torn  into  long,  stringy  fibers.  On  microscopic 
examination  these  are  found  to  be  made  up  of  bundles  of 


HUMAN  AND  ANIMAL  FOODS 


285 


Nutritive  ingredients,  refute,  and  fuel  value. 

Nutrients.  Kon -nutrients. 


Fati. 


Carbo-          Mineral 
hydrates.       matters. 


Water.         Refuse. 


Fuel  value. 


Calories. 


Fuclv8lue7calorl«r~[         400       800      1200      1600     2000     2400 


Sugar 


FIG.  94.  —  Composition  of  food  materials. 


286  CHEMISTRY  AND   DAILY  LIFE 

microscopic  tubes  called  muscle  fibers.  These  fibers  vary 
in  length  in  different  kinds  of  meat.  In  some  meats  they  are 
short,  as  in  the  breast  of  chicken  ;  in  other  cases  they  are  much 
longer,  as  in  the  leg  of  the  crab.  The  shorter  these  fibers  are, 
the  more  tender  and  more  easily  digestible  is  the  meat.  Meat 
should  be  cut  across  the  grain,  that  is,  at  right  angles  to  the  axes 
of  the  fibers,  for  then  it  is  easier  to  chew  it ;  and  since  the 
contents  of  the  tubes  are  better  exposed,  the  meat  is  also  more 
completely  digested.  Gelatin  is  the  chemical  basis  of  all  jellies 
prepared  from  animal  materials.  It  is  a  protein  and  comes 
from  the  connective  tissue  and  bones  of  animals.  On  boiling 
these  tissues  the  gelatines  are  dissolved  and  on  cooling  the 
resulting  solution  sets  to  a  jellylike  mass.  Glue  is  crude 
gelatin.  It  is  commonly  made  from  hide  clippings.  The 
purest  form  of  gelatin  is  isinglass,  which  is  made  from  the 
swimming  bladders  of  fish,  especially  from  those  of  sturgeons. 
Ordinary  gelatin  contains  85  per  cent  of  protein  and  12  to 
13  per  cent  of  water ;  but  the  common  jelly  prepared  for  the 
table  at  home  contains  only  from  2  to  3  per  cent  of  gelatin. 

Fish,  like  meat,  contains  protein,  fat,  and  little  or  no  carbo- 
hydrates. In  localities  near  the  sea,  fish  is  the  cheapest  source 
of  protein.  The  composition  of  the  different  food  fish  is 
somewhat  variable,  but  the  water  content  is  usually  about 
60  per  cent,  the  remainder  being  bones,  protein,  fat,  etc. 
The  protein  content  varies  from  10  to  16  per  cent. 

Next  to  milk,  eggs  are  the  most  wonderful  foodstuff  in  the 
world.  Just  as  milk  contains  the  various  nutritive  constit- 
uents required  by  the  newly  born  young,  so  in  the  egg  there 
are  present  all  of  the  compounds  that  are  necessary  for  the 
new  life  that  lies  dormant  within  its  jellylike  mass.  Out 
of  it  may  come  bone,  hair,  blood,  muscle,  and  feathers.  In 
chemical  language,  the  egg  contains  an  abundance  of  salts, 
proteins,  and  fats,  but  no  carbohydrates.  The  average  weight 


HUMAN  AND  ANIMAL  FOODS  287 

of  a  hen's  egg  is  two  ounces,  about  11  per  cent  of  which  is 
shell,  57  per  cent  is  white,  and  32  per  cent  is  yolk.  The  shell 
is  carbonate  of  lime.  The  white  is  nearly  a  pure  solution  of 
the  protein  albumen,  and  contains  12  per  cent  of  the  latter, 
about  87  per  cent  of  water,  and  1  per  cent  of  ash.  The  yolk 
is  more  complex  than  the  white.  It  contains  from  15  to  16 
per  cent  of  protein,  from  32  to  33  per  cent  of  fats,  50  per  cent 
of  water,  and  1  per  cent  of  mineral  matter.  Some  of  the  fats 
of  the  yolk  are  of  a  special  kind,  called  lecithins ;  these  are  rich 
in  phosphorus  (see  Chapter  IX). 

In  addition  to  the  grains  and  the  various  products  prepared 
from  them,  which  serve  as  food  for  both  man  and  animals, 
there  are  the  bulky  foods  called  forage  which  are  so  common 
on  the  farm.  These  are  the  hays,  straws,  cornstalks,  and  corn 
silage.  As  a  rule  these  fodders  are  rich  in  carbohydrates  and 
poor  in  proteins,  but  they  differ  greatly  among  themselves, 
depending  upon  the  kind  of  plant  from  which  they  are  made. 
Thus  the  hays  made  from  such  plants  as  timothy,  redtop, 
and  June  grass  are  comparatively  poor  in  protein  and  rich  in 
cellulose  or  crude  fiber.  They  contain  about  6  per  cent  of 
protein  and  as  much  as  30  per  cent  of  crude  fiber.  The  rest 
of  the  plant  consists  chiefly  of  available  carbohydrates. 
These  available  carbohydrates,  however,  are  not  really 
starches  and  sugars ;  they  are  more  like  cellulose  in  character. 
In  contrast  to  the  hays  made  from  the  above-named  grasses, 
those  from  the  legumes,  such  as  the  clovers  and  alfalfa,  contain 
from  12  to  15  per  cent  of  protein  and  nearly  as  much  crude 
fiber  and  available  carbohydrates  as  the  hays  of  the  first- 
mentioned  group.  An  acre  of  alfalfa  will  produce  1600 
pounds  of  crude  protein  while  an  acre  of  timothy  will  yield 
but  300  to  400  pounds.  This  is  the  reason  why  the  legume 
hays  are  such  valuable  fodders.  They  serve  as  sources  of 
protein  to  supplement  the  cereal  grains  in  the  ration.  The 


288 


CHEMISTRY  AND   DAILY  LIFE 


cereal  straws,  such  as  those  of  oats,  rye,  wheat,  and  barley, 
are  generally  considered  poorer  feeds  than  timothy,  redtop, 
and  June  grass  hays.  The  straws  are  rich  in  fiber,  often  con- 
taining as  high  as  40  per  cent,  and  have  but  little  protein, 
namely,  from  3  to  5  per  cent.  Corn  stover  —  which  is  left, 


FIG.  95.  — An  alfalfa  field.     The  caps  will  protect  the  hay. 

after  the  ears  have  been  harvested  —  has  a  higher  feeding 
value  than  generally  considered.  It  has  been  found  that  it 
will  nearly  furnish  a  maintenance  ration  for  cattle.  When 
field-cured,  it  contains  about  19  per  cent  of  fiber,  30  per  cent 
of  other  carbohydrates,  40  per  cent  of  water,  and  3  to  4  per 
cent  of  protein. 

It  is  becoming  common  practice  wherever  corn  is  grown  to 
cut  it  before  the  kernel  is  hard  and  glazed  and  store  it  in  a 
silo.  There  are  probably  100,000  silos  in  America,  and  95 
per  cent  of  these  are  filled  with  the  corn  plant.  Silage  can 
be  made  from  beet  leaves,  beet  waste,  pea  vines  from  the  canneries, 
and  to  some  extent  also  from  clover  and  alfalfa ;  but  corn  is  the 


FIG.  96. — A  modern  concrete  silo. 


(289) 


290  CHEMISTRY  AND  DAILY  LIFE 

main  plant  used  at  present  for  this  purpose.  When  harvested 
and  cut,  the  material  is  blown  into  the  silo  and  firmly  packed 
so  as  to  exclude  as  much  air  as  possible.  The  material  in  the 
silo  soon  becomes  warm;  the  sugars  of  the  plants  break 
down  to  acids,  alcohols,  and  carbon  dioxide,  and  some  of  the 
proteins  present  are  partly  digested.  The  acids  formed  are 
mainly  lactic  and  acetic,  and  the  acidity  may  be  as  high  as 
1  to  2  per  cent.  The  formation  of  the  acid  keeps  the  silage 
from  further  decay.  There  are  some  losses  of  dry  matter  in  the 
making  of  silage.  They  have  been  estimated  to  amount  to 
at  least  10  per  cent  under  the  best  conditions  of  handling. 
Nevertheless,  these  losses  are  probably  smaller  than  if  the 
same  material  were  fed  after  it  had  been  cured  on  the  field. 
Silage  is  relished  by  animals,  and  there  is  no  waste  when  it  is 
fed. 

QUESTIONS 

1.  What  is  the  chief  class  of  nutrients  in  vegetable  foods? 
Name  some  foods  in  which  this  is  an  exception. 

2.  Name  the  cereal  grains.    From  which  of  these  is  bread  made  ? 

3.  What  is  the  effect  of  baking  on  the  starch  granules  ?     How 
does  a  very  high  temperature  affect  starches  ?    How  does  it  affect 
some  of  the  proteins  ? 

4.  What  makes  bread  dough  light?    What  is  baking  powder? 

5.  What  is  gluten  feed,  and  how  does  it  differ  from  corn  meal  ? 
What  are  "corn  flakes"  and  "force"  ? 

6.  How  do  beans  differ  in  composition  from  corn  meal  ?     Name 
a  starchy  tuber.     How  much  water  is  there  in  fresh  cabbage? 

7.  How  much  sugar  is  there  in  a  sugar  beet?    What  is  the 
principal  nutrient  in  a  walnut  ? 

8.  What  causes  the  spoiling  of  fruit  ?    How  can  it  be  prevented  ? 

9.  What  is  the  difference  between  a  yeast  and  a  mold  ? 

10.  Name  some  important  foods  of  animal  origin  and  state  their 
chief  characteristics.     Of  what  is  the  shell  of  an  egg  composed  ? 

11.  How  does  timothy  hay  differ  in  composition  from  wheat  flour  ? 
How  does  corn  stover  differ  from  alfalfa  hay  ? 


CHAPTER  XX 
MILK   AND    ITS   PRODUCTS 

DAIRY  products  have  been  used  by  the  human  race  since 
earliest  times,  for  the  oldest  writers  speak  of  milk,  butter,  and 
cheese.  At  present  there  is  scarcely  a  person  in  the  civilized 
world  who  does  not  consume  milk  or  some  of  its  products  every 
day.  The  dairy  industry  is  consequently  of  very  great  im- 
portance. Its  purpose  is  to  furnish  milk,  butter,  cheese, 
and  various  other  products  made  from  milk.  Milk  is  usually 
produced  on  the  farm,  but  occasionally  large  dairies  are  lo- 
cated in  the  city,  where  cows  are  stabled  the  year  around  and 
fed  all  of  their  feed  in  the  manger.  Most  of  the  milk  consumed 
comes  from  cows,  but  in  some  countries  goats'  milk  is  much  used. 
Even  in  America  goats'  milk  is  prized  for  infant  feeding  by 
those  in  charge  of  infant  hospitals. 

Milk  is  secreted  from  the  blood.  In  the  case  of  the  cow  this 
function  is  performed  by  two  large  glands.  While  the  blood 
is  red,  milk  is  never  bloody  unless  the  cow  is  sick.  This  shows 
that  in  making  milk  from  the  blood  very  great  changes  take 
place.  The  milk  is  prepared  from  the  blood  by  the  cells  of  the 
glands.  The  latter  are  rather  soft,  spongy  organs  that  con- 
tain a  fine  network  of  ducts  which  are  lined  with  secreting 
cells.  These  ducts,  which  lead  to  a  small  cistern  located  just 
over  the  teat,  have  their  origin  in  clusters  of  active  secreting 
cells.  The  gland  is  well  supplied  with  blood,  and  at  no  time 
does  it  contain  much  milk.  Most  of  the  milk  is  actually  formed 
while  the  cow  is  being  milked,  but  just  how  this  is  really  done 
is  not  understood. 

291 


292  CHEMISTRY  AND   DAILY  LIFE 

Milk  contains  all  the  food  that  is  necessary  for  the  growth  and 
development  of  young  animals.  It  is  a  complete  food,  and 
through  careful  feeding,  breeding,  and  selecting,  man  has  de- 
veloped the  dairy  cow  so  that  she  now  yields  much  more  milk 
than  is  needed  for  her  offspring,  for  whom  nature  intended 
the  milk.  Some  cows  have  produced  from  ten  to  fifteen  times 
their  weight  of  milk  in  a  year,  or  over  20,000  pounds  ;  but  most 
of  them  give  less  than  one-fourth  of  this  quantity  annually. 
M  ilk  is  composed  of  the  following  substances  :  water,  fat,  casein, 
albumen,  milk  sugar,  and  ash.  A  few  other  substances  are 
present  in  small  quantities,  but  they  are  of  little  practical 
importance.  The  average  percentage  composition  of  cow's 
milk  is  as  follows  : 

Water        87.1  per  cent 

Fat  3.9  per  cent 


Solids        12.9  per  cent 


2.5 


Casein 
Albumen  0.7 
Sugar  5.1 
Ash  0.7 


It  should  be  noted  that  the  percent  of  water  is  very  high,  being 
about  the  same  as  that  in  fresh  vegetables. 

The  composition  of  milk  varies  a  great  deal  with  different 
breeds  of  cows  and  with  the  individual  animals.  The  dairy 
breeds,  such  as  Jerseys  and  Guernseys,  usually  produce  milk 
rich  in  fat,  while  the  milk  from  Holstein  and  Ayrshire  cows  has 
a  lower  percentage  of  this  constituent.  However,  the  breed  of  a 
cow  is  not  a  sure  sign  of  the  richness  of  her  milk;  more 
depends  upon  the  cow  herself.  A  cow  gives  her  largest  flow 
of  milk  after  the  calf  is  a  few  weeks  old,  but  the  nutrients  of  the 
milk  gradually  increase  in  quantity  as  the  period  of  lactation 
advances  and  as  the  flow  decreases.  The  first  milk  drawn  from 
the  udder  is  very  low  in  fat,  while  the  last  fraction,  called 


MILK  AND   ITS  PRODUCTS 


293 


stripper  milk,  will  have  as  much  as  10  per  cent  of  fat.  It  is 
a  common  notion  that  the  fat  of  the  milk  can  be  increased 
by  the  kind  of  feeds  which  a  cow  eats.  But  many  well-con- 


FIG.  97. — A  pure-bred  Jersey  cow. 

ducted  experiments  have  proven  that  such  influence  is  very 
slight,  if  indeed  the  composition  of  milk  can  thus  be  affected  at  all. 
The  fat  occurs  in  milk  in  the  form  of  small  globules.  They 
are  very  minute  in  size  and  it  would  take  about  6000  of 
them  placed  side  by  side  to  make  an  inch.  In  the  milk  of 
Guernsey  and  Jersey  cows  the  average  size  of  the  globules 
is  considerably  larger  than  in  Holstein  milk.  This  explains 
why  the  cream  layer  is  formed  so  much  more  rapidly  in  Guern- 
sey and  Jersey  milk  than  in  Holstein  milk.  The  globules 
of  any  sample  vary  greatly  in  size;  and  the  largest  are  re- 
covered in  the  cream  when  the  milk  is  set,  or  run  through  a 
cream  separator,  while  the  smallest  ones  remain  in  the 
skimmed  milk. 


294 


CHEMISTRY  AND   DAILY  LIFE 


Casein  is  the  principal  nitrogenous  body  in  the  milk  and  gives 
to  the  skimmed  milk  its  bluish  white  color.  It  can  be  sep- 
arated from  the  milk  by  the  addition  of  an  acid,  or  by  the 
action  of  rennet.  In  the  souring  of  milk,  during  which  process 
lactic  acid  is  formed  from  the  milk  sugar  by  bacterial  action, 
the  casein  is  changed  into  a  firm  curd.  To-day  large  amounts 
of  skimmed  milk  are  treated  with  sulphuric  acid.  The 


(A)  (B) 

FIG.  98.  — The  size  of  fat  globules  compared.     (A)  Jersey  milk. 
(B)  Holstein  milk. 

precipitated  casein  is  then  partly  dried  and  used  in  the  manu- 
facture of  knife  handles,  billiard  balls,  and  countless  other 
articles.  When  rennet  is  added  to  milk,  the  casein  separates, 
and  the  fat  is  firmly  held  in  the  curd.  This  forms  the 
starting  point  in  the  manufacture  of  most  forms  of  cheese. 
Junket  tablets  are  dried  rennet.  The  albumen  in  milk  is, 
of  course,  also  a  nitrogenous  compound.  It  is  probably  of 
use  to  the  growing  calf,  but  is  not  used  commercially  as  a 
separate  product.  It  may  be  obtained  by  boiling  the  whey 
which  is  left  after  removing  the  casein. 

Milk  sugar  is  a  carbohydrate  which  has  already  been 
described  (see  Chapter  IX).     It  is  obtained  from  the  milk 


MILK  AND   ITS  PRODUCTS  295 

by  evaporating  the  whey  left  in  cheese  making.  This  sugar 
gives  to  milk  its  sweetish  taste.  When  separated  from  whey,  it 
is  used  in  the  preparation  of  infant  foods,  and  also  as  a  vehicle 
or  carrier  for  certain  medicines.  It  is  the  principal  constituent 
in  whey,  and  gives  the  latter  value  as  a  feed  for  pigs  and  calves. 
The  ash  of  milk  is  the  mineral  matter  that  is  left  after  burning 
off  the  organic  matter.  It  contains  all  of  the  substances  that 
are  necessary  to  build  the  bony  structure  of  the  growing 
animal,  and  furnishes  the  needed  mineral  matter  for  the  for- 
mation of  new  tissue.  The  first  milk  secreted  by  the  cow  after 
the  birth  of  the  calf  is  yellowish  and  rather  thick.  This  is 
called  colostrum  and  is  very  rich  in  albumen,  often  containing 
as  much  as  13  per  cent.  This  first  milk  helps  to  start  the  action 
of  the  digestive  tract  of  the  young  calf  and  is  consequently  very 
important  to  the  latter. 

To  produce  milk  which  is  pure  and  fit  for  drinking  purposes, 
or  for  butter  or  cheese  making,  requires  more  care  than  any 
other  work  on  the  farm.  Careful  attention  must  be  given  to 
the  surroundings  of  the  cow,  to  the  actual  process  of  milking, 
to  the  dishes  in  which  the  milk  is  placed,  and  to  the  place  where 
it  is  kept.  When  dust  gets  into  milk,  it  carries  with  it  small 
one-celled  bodies,  called  bacteria.  These  are  a  form  of  plant 
life ;  they  have  been  mentioned  in  previous  chapters.  At 
favorable  temperatures  these  bacteria  grow  rapidly.  In  24 
hours  a  single  bacterium  may  increase  in  numbers  to  several 
millions,  which  are  all  so  small  that  they  are  not  noticed  ex- 
cept with  a  powerful  microscope.  However,  their  presence  and 
growth  causes  the  milk  to  sour,  for  they  change  milk  sugar 
to  acid.  This  acid  is  principally  lactic  acid,  and  it  causes  the 
milk  to  curdle.  The  common  notion  that  thunderstorms 
cause  milk  to  sour  is  entirely  erroneous. 

Disease-producing  germs  or  bacteria  are  often  introduced 
through  the  dirt  which  gets  into  the  milk.  Scarlet  fever,  tuber- 


296  CHEMISTRY  AND   DAILY  LIFE 

culosis,  typhoid  fever,  cholera,  and  sore  throat  may  be  carried 
and  spread  in  this  way.  The  house  fly  is  a  great  carrier  of 
dirt  and  disease  and  should  be -kept  out  of  the  milk.  Milk, 
too,  has  the  power  of  absorbing  gases  and  odors  and  readily 

acquires  these  from  the  air.  A 
strong  silage  odor  in  the  barn  or 
onion  odor  in  the  refrigerator 
may  be  absorbed  by  the  milk 
and  make  it  objectionable  as  a 
drink.  A  foul-smelling  stable 
will  also  taint  the  milk.  All  of 
these  facts  emphasize  the  necessity 
of  cleanliness  in  milk  production 
and  the  adoption  of  methods  to 
FIG.  99.— A  dirty  fly.  Greatly  check  bacterial  growth.  The 

growth  of  bacteria  can  be  checked 

by  cooling  the  milk  as  soon  as  it  is  produced.  This  pre- 
vents a  rapid  development  of  these  organisms,  but  it  does 
not  entirely  check  their  growth.  Nevertheless,  the  sweet- 
ness of  the  milk  is  prolonged  by  this  cooling  process,  which 
is  a  very  practical  method  and  the  one  usually  followed.  To 
destroy  the  organisms  in  milk  either  heat  must  be  employed  or 
chemical  substances  —  antiseptics  —  must  be  added  to  the  milk. 
If  the  latter  is  heated  enough  to  destroy  all  organisms  (which 
requires  a  temperature  above  100°  C.,i.e.  212°  F.),  it  will  turn 
brown  and  acquire  a  burned  taste.  The  process  of  thus 
destroying  the  organisms  by  heat  is  called  sterilization.  To 
avoid  its  disadvantage,  the  process  known  as  pasteurization 
is  often  substituted.  In  the  process  of  pasteurization  which 
was  originated  by  the  famous  French  chemist,  Pasteur,  and  is 
named  after  him,  the  milk  is  heated  for  twenty  minutes  at 
only  60°  to  80°  C. ;  thus  the  flavor  is  but  slightly  affected, 
and  yet  most  of  the  active  bacteria  are  killed  and  the  keeping 


MILK  AND  ITS  PRODUCTS  297 

qualities  of  the  milk  are  materially  increased.  By  adding 
various  substances  to  milk  the  growth  of  bacteria  can  be 
prevented.  When,  however,  antiseptics  are  added  hi  suffi- 
cient quantities  to  prevent  bacterial  growth,  the  milk  becomes 
unfit  for  human  consumption.  The  chief  preservatives  in 
common  use  are 

1  •    1  !•  O  r*       O    O    •  ^  <•>       •  Q^ 

boric    acid,    sail-  °  «o°fS  o  ° 


cyhc    acid',    for-        ^^fl 

maldehyde,    and  .YJ^o-  &.*  .&J*^** o 

benzoic    acid.  °<O'0  0oVo  o 'ocpi  6^6cn°^° -° ^  C 

Their  use  in  any  V '.$>  .*«  §*8&  foS&Shft 


quantity  is  gen-          6  °~°°    '  u         ^   0 

erally    prohibited       FIG.  lOO.  —  Pure  and  impure  milk.    The  long  black 

bylaw;  and  this 

is  right,  because  when  used  they  show  that  uncleanly  methods 
of  milk  production  are  being  practiced.  Milk  produced  under 
clean,  sanitary  conditions,  and  well  cooled,  will  keep  as  long 
as  it  is  necessary  for  transportation  to  the  city  and  the  con- 
sumer. 

The  fat  of  milk  exists  in  globules  which  tend  to  rise  to 
the  surface  when  the  milk  stands.  After  the  fat  has  been 
removed,  what  is  left  is  called  skimmed  milk.  Cream  is 
milk  with  a  large  amount  of  fat  in  it.  Cream  can  be  separated 
from  milk  by  gravitation,  or  by  the  much  greater  centrifugal 
force  produced  by  rapid  rotation  in  the  centrifugal  separator. 
There  are  two  ways  of  separating  by  gravity,  namely,  the 
shallow-setting  and  the  deep-setting  methods.  In  the  shallow- 
setting,  the  milk  is  placed  in  pans  two  to  four  inches  deep, 
cooled  to  60°  F.,  and  allowed  to  stand  from  24  to  36  hours. 
The  cream  is  then  removed  with  a  slightly  concaved  ladle. 
Not  all  the  fat  is  obtained  in  this  way;  indeed,  only  about 
80  per  cent  of  the  fat  is  usually  thus  removed.  In  the  deep- 
setting  process,  the  milk  is  put  into  cans  twenty  inches  deep 


298 


CHEMISTRY  AND   DAILY   LIFE 


and  less  than  one  foot  in  diameter,  which  are  then  placed  in 
ice-cold  water.  The  cream  rises  rapidly  and  the  operation  is 
practically  complete  in  12  hours.  In  this  way  90  to  95  per 
cent  of  the  fat  can  be  removed,  depending  upon  the  conditions 

of  cooling,  ma- 
nipulation, and 
the  breed  of  the 
cow  whose  milk 
is  thus  treated. 
Because  of  its 
small  globules,  the 
fat  of  the  Hoi- 
stein  milk  cannot 
be  as  completely 
removed  as  that 
of  the  Jersey  milk 
by  this  process. 
Cream  separa- 
tors are  machines 
which  are  now  in 
general  use.  In 
them  the  milk 
runs  into  a  bowl 
which  is  revolv- 
ing several 

FIG.  101. -A  modern  cream  separator.  thousand      times 

a  minute.  This  revolving  tends  to  throw  the  heavy  par- 
ticles to  the  outside  of  the  bowl.  Since  the  fat  is  not  as 
heavy  as  the  other  constituents  of  the  milk,  it  tends  to  come 
to  the  center  of  the  bowl.  The  cover  of  the  bowl  is  so  con- 
structed that  the  cream,  or  fat,  can  escape  from  the  center 
of  the  cover,  while  the  skim  milk  escapes  from  the  opening 
near  the  edge  of  the  bowl.  There  are  many  different  makes 


MILK  AND  ITS  PRODUCTS  299 

of  separators,  but  the  principle  of  operation  in  all  of  them  is 
practically  the  same  as  that  just  described.  These  machines 
recover  from  97  to  98  per  cent  of  the  fat  in  the  milk.  A 
well-operated  separator  rarely  leaves  as  much  as  0.1  per  cent 
of  fat  in  the  skimmed  milk.  A  good  cream  usually  contains 
from  25  to  30  per  cent  of  fat. 

Skimmed  milk  varies  in  composition  according  to  the  more 
or  less  complete  removal  of  the  fat.  It  differs  from  whole  milk 
only  in  its  smaller  content  of  fat,  and  so  it  still  contains  a  val- 
uable amount  of  foodstuffs  which  should  be  used  on  the  farm. 
It  is  excellent  for  feeding  pigs.  Though  poor  in  fat,  machine- 
separated  milk  has  the  advantage  of  being  sweet  and  of  keep- 
ing better  than  the  product  from  other  processes  of  skimming. 

Upon  agitating  cream  or  milk  for  some  time,  the  fat 
globules  coalesce  and  butter  separates  out  in  irregular  masses. 
Churning  is  a  mechanical  process  in  which  the  fat  globules  of 
the  cream  collide  and  adhere;  the  large,  irregular  masses 
thus  formed  then  become  centers  of  growth  to  which  still 
other  fat  globules  adhere.  To  be  of  good  quality,  butter  must 
possess  a  certain  texture  and  grain  and  be  neither  hard  nor 
smeary.  This  desirable  result  can  be  secured  only  by 
churning  at  a  favorable  temperature.  If  the  temperature  is 
too  low,  the  butter  will  be  long  in  coming  and  very  hard.  If 
the  temperature  is  too  high,  the  butter  will  come  quickly, 
but  it  will  be  greasy  and  destitute  of  grain.  The  temperature 
of  churning  should  not  vary  more  than  from  45°  to  65°  F. ; 
indeed,  in  most  cases  from  50°  to  60°  F.  is  chosen  as  the  proper 
range.  In  the  manufacture  of  butter,  the  cream  is  either 
allowed  to  sour  (ripen)  before  it  is  churned  or  is  churned 
directly  without  ripening.  The  former  method  yields  the 
ordinary  market  butter,  the  latter  method  the  sweet  cream 
butter.  In  the  ripening,  acids  and  other  products  are 
formed,  which  give  the  butter  a  high  flavor.  Butter  made 


300  CHEMISTRY  AND   DAILY  LIFE 

from  sweet  cream  is  usually  not  salted.  It  contains  some- 
what more  water,  fat,  and  casein  than  sour-cream  butter. 
Ordinary  market  butter  contains  about  12  per  cent  of  water, 
84.2  per  cent  of  fat,  1.3  per  cent  of  curd,  and  2.5  per  cent  of 
salt.  Under  the  Federal  Pure  Food  Law,  butter  must  con- 
tain 82.5  per  cent  of  fat  and  not  more  than  16  per  cent  of 
water.  During  the  working  of  the  butter  a  part  of  the 
buttermilk  is  squeezed  out.  This  buttermilk  does  not  vary 
much  in  composition  from  the  skimmed  milk. 

Oleomargarine,  which  is  much  used  as  a  substitute  for 
butter,  is  made  by  churning  together  "  oleo  oil,"  "  neutral 
oil,"  milk,  and  a  small  amount  of  cottonseed  oil  and  peanut 
oil.  "  Oleo  oil  "  is  the  liquid  oil  pressed  out  of  beef  fat. 
"  Neutral  oil  "  is  melted  lard.  Some  of  the  oleomargarine  is 
colored  yellow  so  as  to  imitate  butter,  in  which  case  it  is  taxed 
10  cents  per  pound.  Renovated  butter  is  made  from  old  and 
rancid  butter,  by  melting  it,  separating  the  fat  from  the 
casein,  and  blowing  air  through  the  fat  to  remove  the  un- 
pleasant odors  which  are  due  to  volatile  acids  that  have 
formed.  The  liquid  fat  is  then  churned  with  milk,  and  a 
granular  mass  is  obtained  upon  cooling.  This  is  then  worked, 
salted,  and  made  up  as  butter. 

Numerous  kinds  of  cheese  are  made  from  milk.  All  of  the 
casein,  nearly  all  of  the  fat,  and  also  a  large  part  of  the  ash  of 
the  milk  are  present  in  cheese.  The  albumen  and  milk  sugar 
are  in  the  whey.  Only  two  types  of  cheese  which  are  com- 
monly made  in  this  country,  namely,  Cheddar  cheese  and 
cottage  cheese,  will  be  described  here.  Cheddar  cheese  is 
made  by  adding  a  small  amount  of  rennet  extract  to  the  milk. 
The  rennet  is  made  by  extracting  the  fourth  stomach  of  the 
calf  with  a  dilute  salt  solution.  Rennet  contains  a  ferment 
which  causes  the  milk  to  curdle.  In  the  process  of  Cheddar 
cheese  making,  the  milk  is  warmed  to  84°  F.  and  "  ripened  " 


MILK  AND   ITS   PRODUCTS 


301 


to  0.25  per  cent  acidity.  Rennet  is  then  added,  and  when 
the  curd  is  firm,  it  is  cut  into  small  cubes.  In  this  process  the 
fat  has  become  entangled  mechanically  in  the  curd.  The  vat 
is  now  warmed,  which  causes  the  curd  to  shrink  and  harden. 
After  being  maintained  warm  for  one  to  two  hours,  the  whey 
is  drawn  off  and  the  curd  is  piled.  In  this  condition  it  mats 
into  a  solid  mass.  This  is  now  passed  through  a  grinding  mill, 


FIG.  102.  —  A  cheese  curing  room. 

salted,  and  pressed  into  molds.  The  cheese  is  next  put  into 
curing  rooms  at  a  temperature  of  from  50°  to  60°  F.  and  al- 
lowed to  ripen.  When  three  to  four  months  old,  it  is  put  on 
the  market.  The  practice  of  ripening  the  cheese  at  a  tempera- 
ture as  low  as  30°  F.  is  coming  into  general  use.  The  process 
of  making  cottage  cheese  is  substantially  as  follows.  Instead 
of  adding  rennet  to  curdle  the  milk,  it  may  be  allowed  to 
stand  until  it  is  sour;  or  it  may  be  soured  by  adding  a 
"  starter."  A  starter  is  a  powder,  containing  living  bacteria, 


302  CHEMISTRY  AND  DAILY  LIFE 

which  will  slowly  produce  lactic  acid  when  added  to  milk. 
The  curd  thus  obtained  is  strained  from  the  whey,  and  after 
being  salted,  this  makes  sour-milk  or  cottage  cheese. 

The  following  data  will  give  a  general  idea  of  the  composi- 
tion of  cheese.  Cured  Cheddar  cheese  contains  about  34 
per  cent  of  water,  35  per  cent  fat,  28  per  cent  casein  and  3 
per  cent  salt.  Swiss  cheese,  which  is  made  extensively  in 
some  parts  of  this  country,  has  about  the  same  composition. 
Some  types  of  cheese,  as  Camembert  and  Roquefort,  contain 
as  high  as  50  per  cent  of  water.  Milk  is  sometimes  partly 
skimmed  before  being  coagulated  with  rennet,  and  the  prod- 
uct thus  obtained  is  called  skimmed-milk  cheese.  In  many 
states  its  manufacture  is  prohibited. 

There  are  still  other  dairy  products  on  the  market.  Con- 
densed milk  is  manufactured  from  whole  milk  or  partly 
skimmed  milk  by  evaporating  off  a  certain  portion  of  the 
water.  The  milk  is  evaporated  in  large  vacuum  pans  to  one- 
third  or  more  of  its  original  volume.  Condensed  milk  should 
contain  at  least  8  per  cent  of  fat.  In  many  cases  cane  sugar 
has  been  added  in  large  quantities.  This  aids  in  preserving 
the  product,  even  after  the  cans  are  opened.  A  sweetened  con- 
densed milk  may  contain  40  per  cent  of  cane  sugar.  Con- 
densed milk  is  a  good  substitute  for  whole  milk  or  cream,  and  it 
is  used  when  fresh  milk  cannot  be  obtained,  as  on  sea  voyages, 
in  mining  camps,  etc.  Milk  powders  are  made  from  skimmed 
or  partly  skimmed  milk  by  allowing  the  milk  to  evaporate  in 
a  thin  layer  on  a  revolving  drum.  The  product  is  scraped 
off  in  flakes,  and  placed  on  the  market  as  thin,  yellow  scales. 
By  a  later  process  this  powder  is  produced  as  a  fine  flour  and 
this  is  destined  to  be  a  very  efficient  way  of  handling  milk  for 
long  shipment's.  Most  milk  powders  cannot  be  made  from 
whole  milk,  as  the  high  fat  content  of  the  powder  impairs  their 
keeping  quality.  Ice  cream  is  made  from  rich  milk  or  from 


MILK  AND   ITS   PRODUCTS 


303 


cream ;  the  latter  is  the  better.  Ice  cream  consists  of 
milk  or  cream,  sugar,  eggs,  flavoring  material,  and  sometimes 
cornstarch,  gelatin,  or  gum  tragacanth.  The  last  three  sub- 
stances are  added  to  give  the  ice  cream  smoothness  and 
body. 

No  two  things  have  done  more  to  revolutionize  the  dairy 
industry  than  the  cream  separator  and  a  simple  test  for  fat. 


FIG.  103. — A  Babcock  tester  run  by  steam. 

The  cream  separator  is  a  European  invention,  but  the  simple 
efficient  fat  test  for  milk  was  invented  in  America  by  Pro- 
fessor S.  M.  Babcock  of  the  Wisconsin  Experiment  Station 
in  1890.  The  Babcock  test  is  a  simple  means  of  testing  the  milk 
for  its  amount  of  fat.  By  its  use  the  dairyman  can  determine 
which  of  his.  cows  are  paying  their  board,  and  in  this  way  he 
can  definitely  ascertain  the  value  of  a  cow  for  butter  produc- 
tion. Knowing  the  per  cent  of  butter  fat  in  the  milk  and  the 
quantity  of  milk  produced,  it  becomes  an  easy  matter  to 
compute  just  how  much  butter  fat  is  being  produced.  Again, 


304  CHEMISTRY  AND   DAILY  LIFE 

on  the  basis  of  the  test,  milk  can  be  paid  for  on  the  basis  of  its 
fat  content  at  creameries  and  cheese  factories.  Since  the 
Babcock  tester  has  become  an  established  part  of  practically 
every  dairy  equipment,  the  old  and  but  too  common  practice 
of  watering  milk  has  largely  disappeared.  Coupled  with  the 
Babcock  test  for  the  detection  of  water  adulteration  there 
should  be  used  another  equally  important  instrument,  called 
the  lactometer.  This  instrument  resembles  a  floating  ther- 
mometer (see  Fig.  107).  Its  purpose  is  to  determine  the  spe- 
cific gravity  of  milk.  Normal  milk  has  a  specific  gravity  of 
1.029-1.034,  and  if  the  fat  is  partly  removed,  the  specific 
gravity  is  raised ;  but  if  the  adulterator  now  adds  water,  he 
may  bring  the  specific  gravity  back  to  that  of  normal  milk. 
The  use  of  both  tests  detects  such  tampering  with  the  milk. 
For  a  more  just  distribution  of  dividends  at  cheese  factories, 
there  is  coming  into  use  a  simple  mechanical  way  of  estimating 
the  amount  of  casein  in  milk.  This  is  known  as  the  Hart 
casein  test;  it  was  devised  at  the  Wisconsin  Experiment 
Station  in  1907.  This  method  is  almost  as  simple  as  the 
Babcock  test  for  fat,  and  it  will  help  to  solve  the  problem  of 
proper  payment  for  milk  at  cheese  factories.  With  both  the 
fat  and  casein  tests  the  cheese-yielding  capacity  of  the  milk  can 
be  determined. 

QUESTIONS 

1.  What  does  the  milk  of  animals  come  from  ? 

2.  About  how  much  fat  is  there  in  average  milk,  and  how  does 
it  exist  in  the  milk  ?    What  is  this  fat  used  for  ? 

3.  Which  has  the  larger  globules,  Jersey  or  Holstein  milk  ? 

4.  What  is  the  principal  use  of  casein  in  cows'  milk  ? 

5.  How  would  you  obtain  the  milk  sugar  from  milk  ? 

6.  What  precautions  should  be  taken  to  produce  clean  milk? 
What  is  meant  by  pasteurization,  and  sterilization  ? 


MILK  AND   ITS  PRODUCTS 


305 


STEPHEN  MOULTON  BABCOCK.     1843-. 

Scientist  and  inventor  of  the  fat  test  for  milk,  which  bears  his  name, 
test  has  revolutionized  dairying. 

X 


This 


306  CHEMISTRY  AND   DAILY   LIFE 

7.  What  is  an  antiseptic?    Name  two  antiseptics  and  state 
whether  they  should  ever  be  allowed  in  milk.     Give  reason  for  your 
answer. 

8.  Name  three  ways  of  separating  cream  from  milk.     How  much 
fat  is  there  in  good  cream  ? 

9.  Why  does  butter  sometimes  fail  to  come  ?     How  much  water 
is  there  in  ordinary  butter  ? 

10.  Describe  how  oleomargarine  and  renovated  butter  are  made. 

11.  How  is  Cheddar  cheese  made,  and  what  is  its  general  com- 
position ? 

12.  Who  invented  the  commonly  used  fat  test  for  milk,  and  where 
was  it  done  ?    Of  what  importance  is  it  ?    What  two  tests  should 
be  used  at  cheese  factories  for  payment  of  milk  ? 

13.  What  is  a  lactometer,  and  what  is  it  used  for  ? 


CHAFPER   XXI 
POISONS    FOR   FARM    AND    ORCHARD    PESTS 

IN  order  to  have  vigorous,  healthy  plants  and  sound  fruits, 
the  insect  pests  that  are  ever  present  to  feast  upon  them  and 
so  impair  their  growth  or  even  destroy  them  must  be  exter- 
minated. To  kill  off  such  harmful  insects  that  infest  trees 


FIG.  104.  —  Potato  bugs  and  their  eggs. 

and  other  plants,  various  poisons  have  come  into  use.  These 
poisons  are  quite  numerous,  but  they  may  all  be  divided  into  two 
great  classes  according  to  the  type  of  insect  that  is  to  be  destroyed. 
Thus  there  are  pests,  like  the  potato  bug,  that  feed  directly 
on  the  whole  leaf  and  will  consequently  be  killed  by  any 
poison  on  the  leaf.  Such  poisons  which  destroy  because  they 
are  thus  eaten  by  the  insects  are  called  stomachic  poisons. 

307 


308 


CHEMISTRY  AND   DAILY  LIFE 


Again,  there  are  other  insects  like  the  aphides  or  plant  lice 
and  the  San  Jose  scale  that  get  their  nourishment  not  by 
eating  the  whole  leaf,  but  by  merely  sucking  out  its  juices. 
To  exterminate  pests  of  this  kind  requires  a  poison  that  acts 


FIG.  105  (A). — San  Jose  scale  on  an  apple  twig,  slightly  enlarged. 


FIG.  105  (B).  —  San  Jose  scale  on  an  apple  twig,  greatly  enlarged. 

by  enveloping  the  insect  and  thus  corroding  it,  poisoning  it 
by  absorption  through  its  skin,  or  cutting  off  its  opportunity 
to  breathe.  Poisons  that  act  in  this  manner  are  called  con- 
tact poisons. 

Stomachic   poisons    generally   contain    arsenic,    which    is 
present  not  as  the  free  element,  but  either  as  the  oxide  As2O3, 


POISONS  FOR  FARM  AND  ORCHARD   PESTS     309 

also  known  as  white  arsenic  or  arsenious  acid,  or  as  some  more 
complex  arsenical  compound,  like  Paris  Green  or  lead 
arsenate.  The  exact  'composition  of  these  compounds  has 
already  been  given  in  Chapter  VII.  White  arsenic  was  first 
used  as  an  insecticide ;  but  though  not  copiously  soluble  in 
water,  it  nevertheless  dissolves  sufficiently  to  yield  a  solution 
that  corrodes  or  "  burns  "  the  foliage.  It  was  therefore  soon 
discarded.  In  fact,  any  arsenical  poison  that  is  to  be  used  as 
an  insecticide  must  have  wry  little  uncombined  white  arsenic, 
As2Os,  in  it. 

Paris  green  is  at  ^present  the  standard  poison  for  all  insects 
that  bite  and  swallow  their  food.  Its  composition  is  expressed 
by  the  formula  Cu3As2O6  *  Cu(CaHsOi)2.  This  poison  is 
prepared  by  adding  a  hot  solution  of  arsenious  acid  to  a  hot 
solution  of  copper  acetate.  From  this  mixture  Paris  green 
separates  out  as  a  fine  powder  of  a  bright  green  color.  Pure 
Paris  green  is  almost  insoluble  in  water,  but  it  will  readily 
dissolve  in  ammonia  water,  the  resulting  solution  being  dark 
blue.  This  is  a  test  by  means  of  which  certain  impurities  in 
Paris  green  may  be  detected.  Thus,  if  a  sample  of  the  sub- 
stance is  adulterated  with  gypsum,  as  sometimes  occurs,  the 
latter  will  form  a  white  suspension  in  the  ammonia  water  and 
finally  settle  out  on  the  bottom  of  the  glass.  If  no  solids 
separate  out,  it  of  course  only  shows  that  impurities  which  are 
insoluble  in  ammonia  are  not  present.  The  glass  test  may 
also  be  applied.  In  this  test  a  small  amount  of  the  Paris  green 
is  placed  in  a  glass ;  this  is  then  inclined  and  gently  tapped 
so  that  the  poison  will  slowly  move  down  the  inclined  plane. 
In  the  case  of  pure  "  green,"  the  dust  will  be  of  a  bright  green 
color.  If  it  is  impure,  it  may  yield  a  white,  pale-green  streak, 
depending  upon  the  color  of  the  adulterating  substance  that  is 
present.  Examination  under  the  microscope  will  also  help 
to  determine  its  purity.  Paris  green  contains  about  58  per 


310  CHEMISTRY  AND   DAILY  LIFE 

cent  of  arsenious  acid,  31  per  cent  of  copper  oxide  and  10 
per  cent  of  acetic  acid.  These  are  all  chemically  combined 
in  one  compound,  whose  composition  is  indicated  by  the  for- 
mula given  above.  Paris  green  should  not  contain  over  5  per 
cent  of  free  arsenious  acid,  or  it  will  seriously  burn  the  foliage. 
For  use  in  spraying,  from  6  to  8  ounces  of  Paris  green  should 
be  thoroughly  worked  into  a  paste  with  a  little  water,  and  then 
added,  to  50  gallons  of  water.  In  addition,  about  2  pounds  of 
lime  should  be  added;  this  will  neutralize  any  free  arsenious 
acid  present,  and  also  act  as  a  "  marker  "  on  the  sprayed 
plants. 

London  purple  is  an  arsenical  poison  which  was  first  im- 
ported from  England  as  a  substitute  for  Paris  green.  It  is 
prepared  by  boiling  with  slaked  lime  a  purple,  arsenious  acid 
bearing  residue  from  the  dye  industry.  Arsenite  of  lime  is 
thus  formed,  together  with  some  arsenate,  which  contains  more 
oxygen  than  the  arsenite.  London  purple  is  more  injurious 
to  foliage  than  good  Paris  green,  because  of  its  content  of  free 
arsenious  acid.  It  should  always  be  used  with  lime. 

Lead  arsenate  was  recommended  as  an  insecticide  in  1892 
and  was  first  used  against  the  tent  caterpillar.  It  is  pre- 
pared by  adding  lead  acetate  solution  to  sodium  arsenate  also 
dissolved  in  water.  These  substances  dissolve  readily  in 
the  cold  and  react  to  form  sodium  acetate  and  lead  arsenate 
Pb3(AsO4)2.  This  poison  should  be  handled  as  a  paste,  for 
when  once  dried  it  does  not  again  remain  well  in  suspension. 
It  is  the  most  insoluble  of  the  insecticides  now  in  use.  Fur- 
thermore, it  adheres  wry  tenaciously  to  the  leaves  and  is  least 
liable  to  scorch  them.  For  spraying  purposes  two  pounds  of  the 
commerical  paste  in  50  gallons  of  water  is  the  proportion  com- 
monly used. 

Hellebore  is  often  recommended  as  an  insect  poison.  This 
is  the  ground  root  of  the  poke-root  plant.  Pyrethrum,  or 


POISONS   FOR  FARM  AND   ORCHARD  PESTS     311 


insect  powder,  which  comes  from  the  flower  heads  of  certain^ 
plants,  is  another  poison  of  similar  character.  Both  of  these 
materials  contain  poisonous  substances,  but  they  deteriorate 
much  with  age. 

Contact  poisons  may  act  (1)  by  their  caustic  properties,  (2)  by 
poisoning  because  they  are  absorbed  by  the  surface  of  the  insect, 
or  (3)  by  closing  up  the  insect's  breathing  tubes.  Lime-sulphur 
and  kerosene  emulsion  are  types  of  these  poisons.  They  are 
commonly  used 
against  the  scale 
insects.  Lime- 
sulphur  was  first 
employed  in  this 
country  as  a 
sheep  dip,  but  in 
1886  its  use 
against  the  San 
Jose  scale  began. 
It  is  now  either 
purchased  in  the 


FIG.  106.  —  A   simple  home-made  arrangement  for 
making  lime-sulphur. 


commercial  form  or  made  at  home.  It  may  be  prepared 
by  heating  together  80  pounds  of  high  grade  flowers  of 
sulphur,  40  pounds  of  burned  lime,  and  50  gallons  of  water. 
A  rather  pure  lime  should  be  used,  one  that  is  low  in  mag- 
nesium, or  otherwise  there  will  be  a  waste  of  sulphur.  The 
lime  is  first  slaked  in  an  iron  kettle;  and  the  sulphur  is 
separately  thoroughly  mixed  with  &  small  amount  of  water 
and  then  added  to  the  lime,  after  which  the  mass  is  boiled 
for  45  minutes.  The  mixture  is  best  when  boiled  by  passing 
steam  through  it.  During  the  heating  process,  the  lime  com- 
bines with  the  sulphur  forming  calcium  sulphides  of  variable 
composition.  On  standing,  there  results  a  yellow  to  orange 
colored  solution,  under  which  is  an  insoluble  sludge.  This 


312 


CHEMISTRY  AND  DAILY  LIFE 


consists  of  undissolved  sulphur,  calcium  sulphite,  and  calcium 
sulphate.  During  the  boiling,  the  solution  should  con- 
stantly be  kept  up  to  the  50-gallon  mark  by  adding  water 
as  it  evaporates.  When  finished,  the  clear  liquid  should  be 
strained  off  and  tightly  barreled,  because  it  does  not  keep 
in  contact  with  the  air,  which  oxidizes  it. 

For  the  purpose  of  exterminating  scale  insects  the  liquid 
is  diluted  to  test  4.5°  to  5.0°  Baume.  For  summer  work, 
the  solution  is  diluted  with  water  to  test  but 
1°  Baume.  By  this  is  meant  that  the  strength 
of  the  solution  must  be  so  adjusted  that  a 
Baume  hydrometer  (Fig.  107)  will  sink  to  the 
marks  mentioned  before  the  liquid  is  used.  It 
is  believed  that  on  the  tree  the  calcium  sul- 
phides decompose  and  leave  free  sulphur  as 
the  active  agent. 

Kerosene  in  the  form  of  kerosene  emulsion 
is  also  often  used  as  an  insecticide.  Kerosene 
is  a  compound  of  hydrogen  and  carbon  and  is 
prepared  from  crude  petroleum  (see  Chapter 
IX).  It  kills  insects,  and  when  applied  to 
pools  of  stagnant  water,  it  suffocates  the  emerg- 
ing pupse  of  mosquitoes.  When  applied  di- 
rectly to  plants,  it  kills  them.  Kerosene  cannot 
be  diluted  with  water  because  it  will  not  mix 
with  the  latter.  For  this  reason  kerosene  must 
be  mixed  with  some  material  that  will  carry  the  oil,  as  it 
were,  and  keep  it  from  separating  out  from  the  mixture. 
For  this  purpose  a  soap  is  usually  employed.  Kerosene 
emulsion  may  be  made  by  dissolving  one  pound  of  soap  in  2.5 
gallons  of  water,  then  adding  2.5  gallons  of  kerosene  to  the 
solution,  and  thoroughly  mixing  by  pumping  the  entire 
mixture  through  a  bucket  sprayer.  Diluted  to  from  20  to  30 


FIG.  107.  — A 
Baume  hy- 
drometer in 
use. 


POISONS  FOR  FARM  AND   ORCHARD  PESTS     313 

gallons,  the   mixture   may  be    used   against   scale  and  other 
sucking  insects. 

Tobacco  decoctions  can  also  be  used  as  germicides;  as 
such,  their  value  depends  upon  the  poisonous  properties  of  the 
nicotine  they  contain.  This  alkaloid  is  soluble  in  water,  and 


FIG.  108.  —  Plant  lice  (aphis)  on  maple  leaf. 

so  hot  water  extracts  of  the  stalk  and  waste  tobacco  are  made, 
cooled,  and  then  used  as  an  insecticide.  It  is  common  prac- 
tice to  burn  tobacco  in  greenhouses  to  get  rid  of  certain  plant 
lice. 

Gaseous  insecticides  are  often  used  against  insects  that  are 
particularly  difficult  to  attack.  Of  these  substances  hydro- 
cyanic acid  gas  is  the  most  effective.  Cyanides  are  deadly 


314  CHEMISTRY  AND   DAILY  LIFE 

poisons  and  should  never  be  handled  with  the  fingers  (see 
Chapter  IX).  Hydrocyanic  acid  gas  is  made  by  treating 
potassium  cyanide  with  sulphuric  acid.  Two  ounces  of 
concentrated  sulphuric  acid  are  carefully  mixed  with  4  ounces 
of  water;  this  is  placed  in  an  earthenware  vessel  and  then 
1  ounce  of  potassium  cyanide  is  added.  This  is  the  proper 
quantity  for  100  cubic  feet  of  space.  The  gas  is  a  deadly  poi- 
son and  one  breath  of  it  may  be  fatal ;  it  should  therefore  by 
no  means  be  inhaled.  To  retain  the  gas  about  the  plant  and 
make  its  action  effective,  it  should  be  applied  in  tightly 
closed  rooms  or  buildings,  or  under  tents,  as  is  done  in  the 
treatment  of  San  Jose  scale  on  the  orange  trees  of  California. 
The  inclosure  should  afterwards  be  opened  from  the  outside  and 
thoroughly  aired  before  it  is  entered  by  any  one. 

Carbon  bisulphide  is  a  colorless,  volatile  liquid  made  from 
carbon  and  sulphur  (see  Chapter  VII).  The  liquid  is  volatile 
and  its  vapors  are  fatal  to  insects.  Being  heavier  than  air, 
the  vapors  will  settle  through  a  mass  of  grain,  and  so  they  are 
very  effective  in  killing  grain  weevils.  A  teaspoonful  for  each 
cubic  foot  of  space,  placed  in  a  shallow  dish  upon  the  surface 
of  the  grain,  will  kill  the  insects  present.  The  vapors  settle 
down  through  the  grain,  and  may  later,  after  their  work  is 
done,  be  released  by  boring  holes  through  the  walls  of  the  bin. 
Ants,  moles,  prairie  dogs,  and  similar  pests  are  exterminated 
by  placing  cotton  saturated  with  carbon  bisulphide  in  the 
heaps  or  runs,  and  covering  tightly  with  earth.  Carbon  bisul- 
phide should  never  be  brought  near  a  flame,  for  it  is  even  more 
dangerous  than  gasoline. 

Fungicides  are  materials  for  the  destruction  of  certain 
parasitic  plants  called  fungi.  The  chief  fungicide  in  common 
use  is  Bordeaux  mixture,  which  originated  in  France  for  the 
control  of  the  downy  mildew  on  grapes.  It  is  made  by  sus- 
pending 4  pounds  of  copper  sulphate  (also  called  blue  vitriol 


POISONS   FOR   FARM   AND   ORCHARD   PESTS     315 

or  bluestone,  see  Chapter  XI)  in  a  gunny  sack  in  about  15  gal- 
lons of  water.  The  copper  sulphate  dissolves  to  a  clear  blue 
solution.  Six  pounds  of  lime  are  slaked  and  diluted  to  about 


FIG.   109.  —  Students  spraying  an  orchard. 

15  gallons.  The  two  solutions  are  then  mixed  and  diluted 
to  50  gallons.  This  is  the  Bordeaux  mixture.  It  is  a  sus- 
pension of  rather  insoluble  salts  of  copper  and  lime  of  complex 


316  CHEMISTRY  AND   DAILY  LIFE 

composition.  When  applied  to  the  foliage,  the  copper  is 
slowly  brought  into  solution  by  the  action  of  the  carbon 
dioxide  of  the  air,  and  thus  becomes  active  in  destroying 
the  pest.  The  lime  should  always  be  in  excess  in  Bordeaux, 
and  sufficient  in  quantity  so  that  the  mixture  will  turn  red 
litmus  paper  blue.  As  long  as  copper  sulphate  is  in  excess, 
the  reaction  will  be  acid  to  litmus  and  the  scorching  of  the 
foliage  will  follow.  The  potassium  ferrocyanide  test  may 
also  be  used  to  detect  an  excess  of  copper  sulphate  in  solu- 
tion ;  for  when  Bordeaux  mixture  is  filtered  and  a  solution  of 
potassium  ferrocyanide  is  added  to  the  filtrate,  a  brown 
precipitate  of  copper  ferrocyanide  forms  if  free  copper  sul- 
phate is  present.  Bordeaux  mixture  is  a  fungicide,  and  it 
alone  has  no  effective  poisonous  action  upon  plant  insects. 
To  make  it  an  insecticide,  either  Paris  green  or  lead  arsenate 
should  be  added.  This  is  now  frequently  done  in  the  propor- 
tion of  4  ounces  to  50  gallons  of  the  Bordeaux  mixture. 

There  are  still  other  poisons  that  are  sometimes  used  in 
the  home  and  barn  which  must  be  briefly  discussed.  For- 
malin, or  formaldehyde,  is  a  powerful  disinfectant;  that  is,  it 
causes  the  complete  destruction  of  disease  germs.  It  is  a 
product  of  the  oxidation  of  wood  alcohol,  and  is  put  on  the 
market  as  a  38  to  40  per  cent  solution  in  water.  For  killing 
smut  spores  on  grain,  the  seeds  are  immersed  for  ten  minutes 
in  a  solution  of  one  pint  of  the  above  40  per  cent  solution  to 
20  gallons  of  water.  It  must  be  understood  that  formalde- 
hyde is  never  used  as  a  spray  for  foliage.  For  other  purposes 
of  disinfecting,  as,  for  example,  for  use  in  water  closets  or  for 
disinfecting  sick  rooms,  it  has  no  superior. 

Mercuric  chloride,  corrosive  sublimate,  is  another  common 
disinfectant  (see  Chapter  XI).  It  is  put  up  in  tablet  forms 
with  ammonium  chloride  to  hasten  its  solution  in  water. 
One  part  in  1000  makes  a  sufficiently  strong  solution  to  kill 


POISONS  FOR  FARM  AND   ORCHARD  PESTS     317 

most  germs.  Corrosive  sublimate  is  a  stomachic  poison,  and 
forms  insoluble  compounds  with  proteins.  Consequently  an 
antidote  for  it  is  raw  eggs  or  milk. 

Chloride  of  lime  or  bleaching  powder  (see  Chapter  VI) 
is  a  very  common  disinfecting  and  bleaching  agent.  It  is  a 
powder  prepared  by  passing  chlorine  into  slaked  lime.  It 
always  has  a  strong  odor  of  chlorine.  It  is  unstable  and 
slowly  gives  up  its  oxygen,  leaving  calcium  chloride  behind. 
The  oxygen  thus  liberated  is  the  active  agent  which  destroys 
germs  and  other  organic  matter. 

Javelle  water,  which  is  also  used  for  disinfecting  purposes, 
is  made  by  treating  bleaching  powder  with  washing  soda  and 
allowing  the  precipitate  to  settle.  The  clear  solution  is 
employed. 

Lime  alone  is  one  of  the  cheapest  and  most  useful  of  the 
various  disinfectants.  It  will  destroy  organic  matter  as  well 
as  bacteria,  and  therefore  it  is  useful  in  disposing  of  the 
bodies  of  animals  which  have  died  of  some  disease;  it  also 
serves  as  a  whitewash  in  barns  and  pens.  Sixty  parts  of 
water  to  100  parts  of  lime  will  make  a  good  whitewash  or 
"  milk  of  lime  " ;  it  must  be  fresh  to  be  active,  for  air-slaked 
lime  is  the  carbonate  and  has  no  germicidal  power.  When  ap- 
plied with  a  spray  pump,  whitewash  will  enter  the  cracks  in 
stables,  etc.,  and  be  very  effective.  Whitewash,  containing 
a  little  carbolic  acid,  is  an  especially  good  remedy  in  the  poultry 
house  for  lice  and  vermin. 

The  burning  of  sulphur  is  one  of  the  oldest  methods  of  dis- 
infecting;  but  it  is  not  very  reliable.  Sulphur  dioxide  de- 
stroys insects,  vermin,  and  animal  life  in  general,  but  it  does 
not  destroy  the  spores  of  bacteria.  In  order  to  act  at  all, 
sulphur  dioxide  requires  the  presence  of  moisture.  Sulphur 
may  be  procured  everywhere,  and  it  has  the  further  advan- 
tage that  it  is  cheap.  In  fumigating  with  sulphur  proceed  as 


318  CHEMISTRY  AND   DAILY  LIFE 

follows :  In  a  washtub  put  water  to  a  depth  of  about  four 
inches.  In  this,  place  several  bricks  or  flat  stones  so  that  they 
will  protrude  above  the  water  about  two  inches.  Upon  the 
bricks  or  stones,  which  should  be  in  about  the  middle  of  the 
tub,  place  an  old  iron  kettle.  See  that  it  rests  securely  on 
the  bricks.  Now  place  pulverized  sulphur  in  the  kettle, 
from  1  to  3  pounds,  according  to  the  size  of  the  room  to  be 
fumigated.  Open  all  the  doors  of  closets,  cupboards,  etc., 
in  the  room.  Also  spread  out  the  bedding.  Now,  having 
the  washtub  near  the  center  of  the  room,  insert  into  the  heap 
of  sulphur  a  piece  of  blotting  paper  about  3  by  8  inches,  which 
has  been  soaked  in  alcohol.  Wood  alcohol  or  denatured 
alcohol  or  even  strong  rum  or  whisky  will  do.  Mount  this 
paper  so  that  about  3  to  4  inches  will  be  immersed  in  the 
powdered  sulphur.  Now  with  a  match  light  the  upper  end 
of  the  paper.  The  alcohol  will  take  fire  readily  and  burn 
with  a  hot  blue  flame  which  will  be  communicated  to  the 
sulphur.  As  soon  as  the  alcohol  is  burning  well,  leave  the 
room  and  close  the  door  tightly.  After  several  hours,  all 
the  doors  and  windows  may  be  opened  so  as  to  air  the  room 
well.  It  should  not  be  inhabited  till  all  odor  of  sulphur 
dioxide  is  gone.  In  cities  the  health  officer  will  attend  to  the 
fumigation  of  rooms  that  have  been  occupied  by  patients  having 
contagious  diseases. 

Certain  products  that  are  prepared  from  coal  tar  are  also 
good  disinfectants.  Among  these  may  be  mentioned  car- 
bolic acid,  cresol,  creosote,  and  naphthaline.  The  latter 
is  used  in  moth  balls.  Lysol,  carboleum,  germol,  and  zeno- 
leum  are  used  in  dips.  These  are  all  coal  tar  products,  as 
are  also  the  so-called  fly  removers  which  are  sprayed  upon 
animals  to  protect  them  from  flies. 

Some  of  the  advertised  lice  exterminators  contain  tobacco 
and  sulphur  as  the  active  materials.  These  are  not  as  ef- 


POISONS  FOR  FARM  AND   ORCHARD   PESTS     319 

fective  as  lime  and  carbolic  acid.  In  mew  of  the  fact  that  so 
many  of  these  secretly  compounded  materials  are  fraudulent, 
ineffective,  or  very  expensive,  it  is  well  to  be  sure  of  what  the 
mixtures  contain  so  as  to  be  able  to  judge  of  their  worth  before 
purchasing  them. 

It  should  be  remembered  that  nature  has  provided  good, 
efficient  disinfecting  agents,  which,  however,  must  be  allowed 
to  act  freely.  Sunlight  is  a  powerful  germ  killer.  If  sun- 
light could  be  carried  into  every  nook  or  corner  of  the  house 
or  the  barn,  there  would  seldom  be  any  need  of  chemical  dis- 
infectants. The  germs  of  tuberculosis,  diphtheria,  and  typhoid 
fever  are  killed  by  direct  sunlight  in  six  to  eight  hours.  The 
diffused  sunlight  which  reaches  our  rooms  is  not  nearly  so 
powerful  as  direct  sunlight,  and  it  usually  requires  several 
days  for  it  to  destroy  germ  life.  Another  common  agent  for 
killing  bacteria  is  heat.  It  may  be  employed  dry,  as  by  bak- 
ing in  an  oven,  or  moist  as  by  boiling  with  water  or  steam. 
Dry  heat  is  not  as  effective  in  destroying  germs  as  moist 
heat.  All  germs  in  clothing  may  be  destroyed  by  boiling 
it  for  from  five  to  ten  minutes.  Floors  and  walls  may  be  dis- 
infected cheaply  and  efficiently  with  boiling  water  to  which  some 
lye  has  been  added. 

QUESTIONS 

1.  Name  two  ways  in  which  insects  feed.     How  do  the  two 
classes  of  poisons  used  to  exterminate  insects  act  ? 

2.  What  is  the  common  poisonous  ingredient  of  the  stomachic 
poisons  ?    What  is  Paris  green  made  of  ?    Give  two  ways  for  test- 
ing Paris  green  for  purity. 

3.  Why  should  lead  arsenate  be  purchased  as  a  paste  ? 

4.  How  may  lime-sulphur  be  prepared  ?    Why  should  a  high- 
grade  lime  be  used  ? 

5.  For  what  purpose  is  kerosene  emulsion  used  ?    Why  is  soap 
used  in  its  preparation  ? 


320  CHEMISTRY  AND  DAILY  LIFE 

6.  What  is  the  substance  used  in  killing  ants,  gophers,  etc.  ? 
Why  should  flames  be  avoided  when  using  this  substance  ? 

7.  What  is  Bordeaux  mixture,  and  why  should  lime  be  used  in 
excess  in  its  preparation  ? 

8.  What  is  formalin  and  when  can  it  be  used  advantageously  ? 

9.  Name  the  chemical  elements  in  bleaching  powder.     State 
how  it  acts. 

10.  Why  is  whitewash  a  good  material  to  be  used  in  stables  and 
hen-houses  ? 

11.  What  is  the  action  of  sunlight  on  germs  ? 


CHAPTER  XXII 


PRACTICAL   EXPERIMENTS   TO   BE   PERFORMED   IN 
THE   LABORATORY1 

LABORATORY  MANIPULATION 

Cutting  glass  tubing.  Place  the  tubing  on  the  desk,  and 
firmly  draw  the  edge  of  a  triangular  file  across  it  two  or  three 
times  (Fig.  110) 
at  the  place  where 
the  glass  is  to  be 
cut.  Then  take 
the  tube  in  the 
hands  and  with 
the  thumbs  placed 
near  together, 
just  back  of  the 
scratch,  gently  pull  the  glass  apart,  at  the  same  time  pressing 
outward  with  the  thumbs  (Fig.  111).  If  the  tube  does  not 
break,  make  a  deeper  scratch.  If  the  tube  is  large,  it  may 
be  necessary  to  file  around  the  glass.  The  broken  edges  will 
be  sharp  and  should  be  rounded  by  rotating  them  in  the  tip 
of  a  Bunsen  burner. 

Bending  glass  tubing.  Use  an  ordinary  gas  flame,  or  the 
luminous  Bunsen  burner  spread  out  by  a  "  wing  top." 
Hold  the  tube  in  the  flame,  as  shown  in  Fig.  112.  Rotate  the 

1  Lists  of  apparatus  and  chemicals  required  for  these  experiments 
are  given  at  the  end  of  this  chapter.     The  teacher  will  see  to  it  that 
students  use  proper  care  in  handling  flames  and  dangerous  substances. 
Y  321 


FIG.  110.  —  Cutting  glass  tubing. 


322 


CHEMISTRY  AND   DAILY  LIFE 


tube  and  heat  it  until  it 
begins  to  bend  by  its  own 
weight;  then  remove  it 
from  the  flame  and  care- 
fully bend  the  tube  to  the 
desired  shape.  If  the 
tube  is  heated  uniformly 
and  not  too  highly,  the 

bore  of  the  tube  will  not  contract  or  flatten  at  the  bend. 

(See  Fig.  113.) 


FIG.  111.  — Breaking  glass  tubing. 


In 


FIG.  112.  —  Bending  glass  tubing. 


Fitting  corks  to  glass 
tubing.  Select  a  cork  of 
suitable  size  for  the  test 
tube  or  flask  to  be  used. 
Soften  the  cork  by  means 
of  a  cork  press,  or  by  roll- 
ing it  between  the  desk 
and  a  block  of  wood. 
Select  a  cork  borer 
slightly  smaller  than  the 
tube  to  be  inserted. 
Place  the  cork  on  the 
desk  and  bore  through  it,  FlG>  113'~Goodt^ngad  bends  °f  glass 


PRACTICAL  LABORATORY  EXPERIMENTS       323 


not  by  merely  pressing,  but  by  rotating  the  borer  under 
slight  pressure,  as  in  using  a  gimlet.  Keep  the  borer  up- 
right and  at  right  angles 
to  the  cork.  If  the  hole 
is  too  small,  a  round  file 
may  be  used  to  enlarge  it. 
Pouring  liquids  from 
bottles.  Remove  the 
bottle  from  the  shelf, 
lift  the  stopper  with  the 
fingers,  as  shown  in  Fig. 


114,  and    pour   into    the 


Fig.  114.— Pouring  from  a  bottle. 

test  tube.  When  the  required  amount  of  acid  has  been 
poured  out,  touch  the  neck  of  the  bottle  with  the  test 
tube  to  catch  the  drops  on  the  edge  and  thus  prevent 
them  from  streaking  down  the  side  of  the  bottle  and 


FIG.  115.  —  Pouring  from  a  beaker. 


324 


CHEMISTRY  AND  DAILY  LIFE 


on  to  the  shelf  or  table.  When  pouring  from  one  beaker 
into  another,  a  glass  rod,  held  as  shown  in  Fig.  115,  will  pre- 
vent the  liquid  from  running 
down  the  side  of  the  beaker. 

Filtering.  This  ordinarily 
has  for  its  purpose  the  separa- 
tion of  a  liquid  from  a  solid. 
Place  the  funnel  in  the  arm  of 

a  wooden  stand.  Fold  the  filter  paper  into  halves  and  then 
at  right  angles  into  quarters  (Fig.  116).  The  folded  filter 
paper  is  opened  so  as  to  form  a  cone  half  of  which  is  three 
thicknesses  of  paper  and  the  remainder  one  thickness.  Now 
fit  the  cone  into  a  funnel  of  such  a  size  that  the  edge  of  the 
paper  does  not  quite  reach  the  top.  If  the  paper  does  not 


FIG.  116.  —  Folding  a  filter. 


FIG.  117.  — A  filter  ready  for  use. 

fit,  vary  the  folding  slightly  until  it  does.  Now  place  the 
paper  into  the  funnel  and  moisten  it  so  that  it  adheres  to  the 
sides  of  the  funnel.  Press  the  paper  gently  with  the  fingers 
against  the  side  of  the  funnel  to  remove  any  air  bubbles. 
The  filter  is  now  ready  for  use  (Fig.  117). 


PRACTICAL  LABORATORY  EXPERIMENTS   325 

Heating  liquids  in  test  tubes.  Fill  the  test  tube  only  about 
one-third  full.  Hold  it  between  the  fingers  and  thumb,  and 
constantly  rotate  it  in  the  flame  so  as  to  apply  heat  uniformly. 
The  heat  should  be  applied  to  the  upper  end  of  the  liquid 
and  not  to  the  bottom  or  to  the  glass  above  the  liquid,  as 


FIG.  118.  —  Heating  a  liquid  in  a  test  tube. 

shown  in  Fig.  118.     A  test-tube  holder  or  a  band  of  paper 
may  be  used  to  hold  the  tube. 

In  the  following  experiments  the  student  should  record  his 
observations  and  conclusions  neatly  and  carefully  in  a  labora- 
tory notebook,  which  is  to  be  submitted  to  the  teacher  for  cor- 
rections and  suggestions  upon  completion  of  each  experi- 
ment. 


326  CHEMISTRY  AND   DAILY  LIFE 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  I 

1.  Chemical   and    physical   changes.     Examine   a   piece 
of   rock   candy.     Notice   its    properties,  such  as  its  color, 
taste,  hardness,  and  crystalline    form.     Describe  its   taste. 

(1)  Grind  a  piece  in  a  mortar.     Has    the   taste  changed? 

(2)  Partly  fill  a  beaker  with  water,  and  add  a  little  of  the 
powdered  candy  and  stir  with  a  glass  rod.     Taste  the  solu- 
tion.    Does  the  sugar  still  exist?     (3)  Heat  5  grams  of  the 
powdered  candy  in  a  dry  test  tube,  applying  the  heat  gently 
at  first,  and  noting  carefully  the  changes.     When  no  further 
change  takes  place,  even  at  a  much  higher   temperature, 
allow  the  tube  to  cool.     Taste  the  residue.     Will  it  dissolve 
in  water?    Notice  its  color.     What  does  the  new  substance 
resemble?    Has  there  been  a  chemical  change?     (4)   Heat 
a  platinum  wire  or  a  piece  of  porcelain,  and  then  let  it  cool. 
Was  there  a  change  in  this  case  ?    Was  it  physical  or  chemical  ? 

2.  Compounds  and  mixtures.     (1)    Note  the  visible  prop- 
erties of  a  piece  of  sulphur.     Test  it  with  a  magnet.     Is 
it  attracted  ?     Drop  a  piece  of   roll   sulphur,  as   large  as  a 
pea,  in  a  test  tube  and  add  5  to  10  cc.  of  carbon  bisulphide 
and  shake.     Use  carbon  bisulphide  sparingly.     Remember 
to  have  no  flame  in  the  room  while  working  with  it,  for  it 
is  more  dangerous  than  gasoline.     Does  the  sulphur  dis- 
solve?    Pour  off  the  liquid  from  the  undissolved  sulphur 
into  a  watch  glass,  and  let  it  evaporate.     Is  there  a  residue 
on    the   watch    glass  ?     Is   it    like    sulphur  ?     (2)  Examine 
some  powdered  iron.     Test  it  with  a  magnet.     See  if  it  will 
dissolve  in  carbon  bisulphide.     (3)  Stir  together  3  grams  of 
powdered  sulphur  and  5  grams  of  powdered  iron.     What  is 
the  color  of  the  new  powder  ?    Bring  a  magnet  to  some  of  the 
mixture.     Does  the  iron  still  exist  ?    Put  some  of  the  powder 
in  a  test  tube,  add  carbon  bisulphide,  shake,  pour  off  the 


PRACTICAL  LABORATORY  EXPERIMENTS       327 

liquid,  and  evaporate  some  of  it  on  a  watch  glass.     Does  the 
sulphur  still  exist  in  the  mixture  ? 

3.  Chemical  change.     Heat  the    rest  of  the  mixture  of 
sulphur  and  iron  from  the  above  experiment  in  a  test  tube 
with  a  small  flame.     When  the  mass  begins  to  glow  like  a 
red-hot  coal,  remove  the   tube  from   the   flame.     Lay  the 
tube  down  to  cool.     There  is  probably  a  little  melted  sul- 
phur part  way  up  the  inside  of  the  tube.     Do  not  allow 
this  to  run  down  and  mix  with  the  substance  at  the  bottom 
of  the  tube.     When  the  tube  is  cool,  break  it  open  and  ex- 
amine the  substance  in  the  bottom  where  the  glow  had  been. 
See  if  any  sulphur  can  be  dissolved  out  of  it  with  carbon  bi- 
sulphide.    Test  the  black  material  with  a  magnet.     Can 
you  detect  either  sulphur  or  iron  in  the  new  substance  ? 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  II 

4.  Electrolysis  of  water.     This  experiment  is  to  be  done 
by  the  instructor.     Set  up  the  apparatus  as  shown  in  Fig.  1. 
The  water  used  should  be  slightly  acidulated  with  sulphuric 
acid,  for  pure  distilled  water  will  not  conduct  the  electric  cur- 
rent sufficiently  well.     Three  or  four  dry  cells  will  suffice. 
Note  the  difference  in  the  volume  of  gas  formed  in  the  two 
arms. 

5.  Explosion  of  hydrogen  and  oxygen  mixture.     This  ex- 
periment is  to  be  done  by  the  instructor,  who  will  prepare 
oxyhydrogen  gas  by  electrolysis  of  water,  and  then  pass  the 
mixture  into  the  eudiometer  tube  over  mercury.    The  ex- 
plosion is  effected  by  means  of  the  electric  spark,  the  appara- 
tus for  this  purpose  being  arranged  as  shown  in  Fig.  2. 

6.  Salts  in  well  water.     Place  some  ordinary  service  or 
well  water  on  a  watch  glass,  and  set  it  in  a  warm  place  to 
evaporate.     The  evaporation  will  proceed  best  by   placing 


328  CHEMISTRY  AND   DAILY  LIFE 

the  watch  glass  on  a  hot  water  bath.     Note  the  residue  left 
in  the  dish. 

7.  Preparation  of  distilled  water.     Set  up  an  apparatus 
as  shown  in  Fig.  3.     Place  from  200  to  300  cc.  of  water  in  the 
flask.     Apply  heat  gently,  and  collect  100  cc.  of  the  distilled 
water.     Be  sure  that  cold  water  is  running  through  the  con- 
denser.    Observe   the  difference  in  the   taste  and    odor  of 
the  water  before  and  after  distillation.     Evaporate  a  few 
cubic  centimeters  of  the  distillate  by  gentle  heat  on  a  clean 
watch  glass.     Is   there  any  residue   left?     How  does   this 
result  compare  with  that  of  experiment  6? 

8.  Water  in  various  substances.     (1)  Take  some   green 
leaves  of  any  plant,  also  a  carrot,  or  a  potato  to  represent  a 
root,  and  some  wheat  or  corn  as  samples  of  seed.     Weigh  out 
50  grams  of  each  in  weighed  dishes  of  tinned  iron  or  porce- 
lain.    Then  put  the  dishes  in  a  warm  place  and  cover  each 
of  them  with  a  glass  plate.     Window  glass  will  do.     In  a  few 
minutes  the  plates  will  be  dimmed  over  with  water  that  has 
been  driven  out  of   the  plant  by  heat.     Save  the  materials 
for  experiment  9.     (2)  Heat  pieces  of  beef,  old  mortar,  and 
epsom  salts  each  separately  in  a  large  test  tube  and  observe 
the  water  that  condenses  on  the  side  of  the  tube  (see  Fig.  4). 
The  pieces  to  be  heated  should  be  of  about  the  size  of  a  small 
hickory  nut. 

9.  Amount  of  water  in  a  plant.     When  it  has  been  seen 
that  the  plant  tissue  in  experiment  8  is  losing  water,  remove 
the  glass  covers  and  put  the  dishes  in  the  open  air  or  on  the 
water  bath  to  dry.     This  will  require  a  day  or  so.     On  re- 
weighing  the  dishes,  it  will  be  found  that  the  contents  have 
lost  a  good  deal  of  water ;  80  to  90  per  cent  in  the  case  of  the 
green  leaves.     The  roots  lose  nearly  as  much,  while  the  seeds 
lose  only  from  10  to  15  per  cent.     Saw  the  material  for  ex- 
periment 10. 


PRACTICAL  LABORATORY  EXPERIMENTS       329 

10.  Ash  in  a  plant.     Take  the  residue  from  experiment 
9  and  heat  it  gently  over  a  flame  in  a  porcelain  dish  until 
everything  possible  has  been  burned  off.     There  will  remain 
a  gray  or  white  ash  which  may  amount  to  from  2  to  5  per 
cent  of  the  dry  matter  that  was  left  after  removing  the  water. 
In  the  plant  ash  only  a  few  elements  are  found,  but  these  are 
the  same  whatever  the  plant,  or  wherever  it  was  grown.     The 
elements  in  the  ash  are  present  as  phosphates,  sulphates, 
carbonates,  chlorides,  and  silicates.     The  teacher  will  show 
the  presence  of  calcium  and  phosphorus  in  the  ash  by  simple 
qualitative  tests. 

11.  Deposits  of   lime  by  boiling  water.     Boil  for  a  few 
minutes  about  200  cc.  of  hard  well  water  or  " White  Rock" 
mineral  water  in  a  flask.     After  the  water  is  cool,  note  any 
sediment  of  lime  or  turbidity  of  the  water.     Boiling  has  ex- 
pelled the  carbon  dioxide,  which  has  held  the  carbonates  of 
lime  and  magnesia  in  solution.     When  this  carbon  dioxide 
is  driven  off,  the  carbonates  precipitate.     The  crust  in  tea- 
kettles and  the  scale  in  boilers  are  chiefly  of  this  nature. 
These  deposits  interfere  with  good  heating  and  steaming. 

12.  Hard  and  soft  water.     Place  about  50  cc.  of  very 
hard  water  in  a  200-cc.  cylinder  or  flask.     This  water  may  be 
prepared,  if  necessary,  by  adding  0.1  or  0.2  gram  of  calcium 
chloride  to  500  cc.  of  ordinary  water.     Add  to  this  a  measured 
quantity  of  soap  solution,  made  as  stated  below.     Mix  well, 
and  notice  how  much  soap  solution  must  be  added  before 
a  permanent  lather  is  formed.     Also  notice  the  precipitate 
of  lime  soap.     Repeat  the  experiment,  using  rain  water  and 
tap  water  respectively.     Which  of  these  waters  requires  the 
most  soap  solution  ?     Hardness  of  water  is  due  to  the  lime 
and  magnesia  salts  in  solution.     To  prepare  the  soap  solution, 
scrape  10  grams  of  castile  soap  to  fine  shavings,  and  dissolve 
these  in  a  liter  of  denatured  alcohol ;  then  dilute  with  water 


330 


CHEMISTRY  AND   DAILY  LIFE 


to  1350  cc.     If  the  solution  is  not  clear,  filter  it.     Keep  it  in 
a  tightly  stoppered  bottle. 


EXPERIMENTS  TO  ACCOMPANY  CHAPTER  III 

13.  Preparation  of  hydrogen.  Place  from  15  to  20  grams 
of  granulated  zinc  in  a  flask  arranged  as  shown  in  Fig.  119. 
Cover  the  zinc  with  25  cc.  of  water.  The  thistle  tube  should 
dip  below  the  water.  Fill  two  or  three  cylinders  with  water 
for  collection  of  the  gas  in  the  pneumatic  trough.  See 


FIG.  119.  —  Hydrogen  generator. 


that  the  stopper  is  tight,  for  hydrogen  easily  escapes.  When 
all  is  ready,  add,  through  the  thistle  tube,  about  15  cc.  of 
concentrated  hydrochloric  acid.  Do  not  apply  any  heat. 


PRACTICAL   LABORATORY  EXPERIMENTS       331 

Do  not  collect  any  gas  until  the  generator  has  run  for  at  least 
two  minutes.  Wrap  a  towel  securely  around  the  generator, 
and  then  collect  a  test  tube  full  of  the  gas  and  light  it.  If  it 
burns  quietly  without  explosion,  proceed  to  collect  a  cylinder 
or  small  bottle  (100  cc.)  of  gas.  (1)  Introduce  a  burning 
splinter  into  the  gas;  does  it  support  combustion?  (2) 
When  the  generator  has  been  running  for  some  time  —  five 
to  six  minutes  —  disconnect  at  A,  attach  the  blowpipe  tip 
B,  and  light  the  gas.  Explosions  will  occur  if  the  air  is  not 
all  displaced.  Hold  an  inverted  clean  dry  beaker  over  the 
flame ;  note  the  production  of  water  by  the  combustion.  The 
hydrogen  unites  with  the  oxygen  of  the  air  to  form  water. 
Use  your  brass  blowpipe  as  a  jet  when  lighting  the  gas, 
and  note  the  color  of  the  flame.  The  hydrogen  flame  is 
colorless. 

14.  Action  of   sodium  on  water.     In   your  evaporating 
dish  place  20  cc.  of  water  and  then  drop  into  it  a  piece  of 
sodium  half  as  large  as  a  pea.     After  the  action  has  entirely 
ceased,  test  the  solution  with  red  litmus  paper.     What  com- 
pound is  dissolved  in  the  water  ? 

15.  Preparation    of    oxygen.     Set    up  the    apparatus  as 
shown  in  Fig.  120.     Fill  the  pneumatic  trough  nearly  full 
of  water  and  place  in  it  the  free  end  of  the  delivery  tube. 
Weigh  out  5  grams  each  of  potassium  chlorate  and  manganese 
dioxide.     Mix  these  on  a  paper  and  place  the  mixture  in  the 
test  tube.     Have  the  test  tube  perfectly  dry  inside  and  out. 
Fill  several  cylinders  with  water,  cover  these  with  glass  plates, 
and  invert  them  on  the  shelf  of  the  trough,  removing  the 
plates.     With  a  small  flame,  apply  heat  cautiously  to  the  test 
tube.     The  burner  should  be  held  in  the  hand,  so  that  the 
flame  may  be  removed  from  time  to  time ;    it  should  not  be 
allowed  to  strike  in  one  spot,  otherwise  the  glass  may  crack. 
As  soon  as  gas  comes  off  freely,  place  the  end  of  the  delivery 


332 


CHEMISTRY  AND  DAILY  LIFE 


•  tube  so  that  the  gas  is  collected  in  one  of  the  cylinders. 
When  the  cylinder  is  filled,  cover  it  with  one  of  the  glass  plates 
while  still  under  water.  It  can  then  be  placed  upright  on 
the  desk,  while  another  cylinder  is  being  filled.  After  thus 
filling  two  or  three  cylinders,  remove  the  end  of  the  delivery 
tube  from  the  water,  and  then  remove  the  flame.  Do  not 
remove  the  flame  while  the  delivery  tube  is  under  water.  If  you 


FIG.  120.  —  Making  oxygen. 

do,  a  vacuum  will  be  formed  and  the  water  will  be  forced  into 
the  hot  tube  and  break  it.  (1)  Light  a  splinter  and  place 
it  for  a  moment  in  one  of  the  cylinders ;  remove  it  and  ex- 
tinguish the  flame,  but  while  still  glowing,  thrust  it  into  the 
cylinder  again.  (2)  Put  a  small  piece  of  sulphur,  no  larger 
than  a  grain  of  wheat,  into  a  small  iron  spoon.  Ignite  the 
sulphur  in  a  flame  and  thrust  the  burning  material  into  a 
cylinder  of  oxygen.  Record  the  results.  (3)  Heat  the  end 
of  a  piece  of  fine  iron  wire.  Dip  into  it  flowers  of  sulphur, 
light  the  sulphur,  and  plunge  the  wire  into  a  cylinder  of 
oxygen  while  the  sulphur  is  still  burning.  What  is  the  result  ? 
(4)  Heat  a  piece  of  charcoal  in  the  air,  and  while  it  is  still  glow- 
ing drop  it  into  a  cylinder  of  oxygen.  What  is  the  result  ? 
Now  shake  the  contents  of  the  cylinder  with  5  cc.  of  water ; 


PRACTICAL  LABORATORY  EXPERIMENTS       333 

then  test  the  water  with  a  piece  of  blue  litmus  paper.  Also 
add  clear  limewater  and  shake  the  contents.  Record  the  re- 
sults and  explain  your  observations. 

16.  Ozone  by  electric  sparks.     Work  a  frictional  electric 
machine  and  note  the  odor  produced  in  the  air.     Ozone 
has  been  formed  by  the  electric  discharges. 

17.  Ozone.    Smell    of  a  bottle    containing   yellow    phos- 
phorus in  water.     The  odor  of  ozone  can  be  detected. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  IV 

18.  Carbon  dioxide  in  the  air.     Pour  10  cc.  of  perfectly 
clear  limewater  (calcium  hydroxide)  into  a  test  tube  and  blow 
air  through  it,  using  for  the  purpose  a  clean  glass  tube.     Ob- 
serve the  precipitate  of  calcium  carbonate.     Expose  some 
clear  limewater  to  the  air  in  a  beaker  for  24  hours  and  ob- 
serve the  result.     There  is  a  small  amount  of  carbon  dioxide 
in  the  air  and  this  is  the  plant's  source  of  carbon. 

19.  Preparation  of  nitrogen.     Float  a  thin  piece  of  cork 
on  a  surface  of  water  in  the  pneumatic  trough.     Place  on  it 
a  piece  of  phosphorus  half  as  large  as  a  pea.     Note :   Phos- 
phorus is  very  dangerous.     Handle  it  with  a  forceps.     Keep 
it  under  water  till  you  actually  require  the  piece  for  use. 
Use  no  more  than  directed.     Ignite  the  phosphorus  with  the 
end  of  a  hot  wire,  and  quickly  place  over  it  a  wide-mouthed 
bottle  filled  with  air,  being  careful  to  keep  the  mouth  of  the 
bottle  under  water.     Let  the  gas  stand  over  water  until 
the  white  fumes  are  absorbed.     The  white  fumes  are  phos- 
phorus pentoxide.     Note  the  extent  of  the  rise  of  the  water 
in  the  bottle.     (1)  Now  test  the  gas  with  a  lighted  splinter. 
Does    it    support    combustion?     (2)    Place    some    burning 
sulphur  on  a  spoon  and  insert  it  in  the  nitrogen.     How  does 
it  behave  ? 


334  CHEMISTRY  AND   DAILY  LIFE' 

20.  Preparation  of  nitric  acid.  Special  care  should  be 
exercised  by  the  student  in  the  preparation  of  all  acids;  but 
with  nitric  acid  special  care  must  be  taken,  because  if  any 
is  spilled  on  the  hands  it  causes  painful  burns  and  wounds  that 
heal  slowly.  Arrange  the  apparatus  as  shown  in  Fig.  121. 
Carefully  introduce  25  grams  of  sodium  nitrate  and  then  25 


FIG.  121.  —  Making  nitric  acid. 

grams  of  concentrated  sulphuric  acid  into  the  retort,  and 
shake  very  gently  until  all  is  well  mixed.  Heat  the  mixture 
gently  and  collect  the  nitric  acid  in  a  test  tube,  cooled  by 
water.  Make  the  following  tests  :  (1)  Remove  a  drop  of  the 
acid  by  means  of  a  glass  tube  and  apply  it  to  a  piece  of  woolen 
cloth  or  silk ;  observe  the  result.  (2)  Place  a  few  drops  of 
indigo  solution  in  a  test  tube  containing  5  cc.  of  water  and 
then  add  2  cc.  of  nitric  acid.  What  happens  ?  (3)  Place  a 
small  piece  of  copper  in  the  test  tube  containing  the  remain- 
der of  the  acid.  If  no  reaction  takes  place,  add  a  little  water. 
What  becomes  of  the  copper  ? 

21.  Preparation  of  ammonia.  Arrange  apparatus  as  shown 
in  Fig.  122.  Into  the  flask  place  10  grams  of  ammonium 
chloride,  10  grams  of  powdered  lime,  and  25  cc.  of  water. 


PRACTICAL  LABORATORY  EXPERIMENTS       335 

When  the  apparatus  is 
properly  connected,  ap- 
ply heat  gently  for  8  to  10 
minutes.  (1)  Test  the 
gas  with  red  litmus 
paper.  (2)  Test  the  gas 
with  a  burning  splinter. 
(3)  Into  an  evaporating 
dish  place  5  cc.  of  hy- 
drochloric acid  and  10 
cc.  of  water,  and  pour 
this  into  a  cylinder  of  the 
gas.  Avoid  inhaling  any 
of  the  ammonia  gas.  The 
white  fumes  are  ammo- 
nium chloride.  Why  did 
you  collect  the  ammonia 
gas  in  an  inverted  cylin- 
der? What  is  formed 
when  ammonia  gas  is 

treated    with    Water?  FIG.  122.  —  Making  ammonia. 

Shake  a  cylinder  of  am- 
monia gas  with  25  cc.  of  water,  and  test  the  solution  with 
red  litmus  paper. 


EXPERIMENTS  TO  ACCOMPANY  CHAPTER  V 

22.  Acids  in  fruits  and  silage.  (1)  Cut  open  a  lemon 
and  squeeze  some  of  the  juice  into  a  beaker.  Add  a  few 
drops  of  phenolphthalein  solution  and  then  carefully  add 
a  dilute  solution  of  potash  or  baking  soda  until  the  red  color 
just  appears.  Note  the  lowering  of  the  acid  taste  as  the 
potash  is  added.  Lemons  contain  citric  acid.  This  ex- 


336  CHEMISTRY  AND   DAILY  LIFE 

periment  may  be  repeated  with  grapes  in  which  the  main 
acid  is  tartaric  acid.  From  the  grapes  we  get  cream  of 
tartar.  (2)  Press  the  juice  from  silage,  and  neutralize  the 
acids  in  this  in  the  same  way.  In  silage  the  acids  are  mainly 
acetic  and  lactic  acids. 

23.  Acids   and   bases.     Preparation   of   a  salt.     Put  10 
cc.  of  dilute  hydrochloric  acid  and  10  cc.  of  water  in  a  porce- 
lain dish.     Measure  out  10  cc.  of  sodium  hydroxide  solution 
into  a  beaker,  and  add  50  cc.  of  water.     Add  this  dilute 
sodium  hydroxide  to  the  acid,  a  little  at  a  time,  until  the 
solution  is  neutral  to  litmus.     Do  not  drop  the  paper  into  the 
solution,  but  by  means  of  a  glass  rod  transfer  a  drop  of  the 
solution  to  the  paper.     In  case  too  much  sodium  hydroxide 
has  been  used,  add  a  drop  or  two  of  the  acid.     Bases  or 
alkalies  turn  red  litmus  blue,  while  acids  turn  blue  litmus  red. 
When  the  solution  is  neutral,  it  has  no  perceptible  action  upon 
litmus  paper.      Place  the  dish  upon  a  sand  bath  and  apply 
heat  until  the  solution  is  evaporated  to  dryness.     Avoid 
excessive  heating.     This  will  prevent  spattering  when  the 
solution  becomes  concentrated.     Taste  some  of  the  material 
in  the  dish.     It  is  common  salt  and  entirely  different  in 
taste  and  chemical  action  from  either  hydrochloric  acid  or 
sodium  hydroxide.     It  is  formed  by  the  union  of  an  acid 
and  a  base.     Write  the  equation. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  VI 

24.  Preparation  of  hydrochloric  acid.     Into  a  generator, 
arranged  as  in  Fig.   119,  place  15  grams  of  common  salt. 
Through  the  funnel  tube  add  25  cc.  of  concentrated  sul- 
phuric acid.     Warm  the  mixture  gently  if  necessary.     Let 
some  of  the  gas  bubble  through  water  in  a  receiving  flask. 
Test  the  liquid  with  litmus  paper.     Taste  it  carefully.     Take 


PRACTICAL  LABORATORY  EXPERIMENTS       337 

away  the  water,  and  collect  some  of  the  gas  in  a  bottle  by 
displacement  of  air.  Is  the  gas  heavier  or  lighter  than  air  ? 
Does  the  gas  burn?  Hold  a  filter  paper  moistened  with 
ammonia  near  the  escaping  gas.  Explain,  and  write 
the  equation.  Invert  a  jar  of  the  gas  over  water.  What 
causes  the  water  to  rise  ?  To  some  of  the  solution  add  a  few 
drops  of  silver  nitrate.  A  precipitate  is  formed  which  is  the 
very  insoluble  silver  chloride. 

25.  Chlorides  in  water.     To  test  for  chlorides,  add  a  few 
drops  of  nitric  acid  to  10  cc.  of  water  and  then  add  5  cc.  of  a 
1  per  cent  solution  of  silver  nitrate.     The  formation  of  a  white 
precipitate  of  silver  chloride  indicates  chlorides.      Try  this  on 
well  water  and  on  service  water,  also  on  a  0.1  per  cent  solu- 
tion of  common  salt. 

26.  Bleaching    action    of    bleaching    powder.     Place    20 
grams  of  bleaching  powder  in  a  beaker.     Cover  the  powder 
with  water,  and  then  add  40  cc.  of  10  per  cent  sulphuric  acid. 
Hang  a  moist  strip  of  red  calico  in  the  beaker  by  means  of 
a  wire.     Now  cover  the  beaker  with  a  glass  plate,  warm 
gently,  and  let  it  stand.     What  is  the  result  ?     Turkey  red 
calico  will  be  almost  unchanged,  but  other  cheaper  calicoes 
will  be  altered. 

27.  Vapors  of  iodine.     Place  1  gram  of  potassium  iodide 
and  an  equal  amount  of  manganese  dioxide  in  a  test  tube, 
and  then  add  2  cc.  of  concentrated  sulphuric  acid.      Warm 
gently.     Note  the  violet  color  of  the  vapors  formed.     These 
are  the  vapors  of  iodine. 

28.  Vapors  of  bromine.     Mix  1  gram  of  pulverized  po- 
tassium bromide  and  1  gram  of  manganese  dioxide.     Place 
this  mixture  in  a  test  tube,  add  2  cc.  of  concentrated  sul- 
phuric acid,  and  heat  gently.     Note  the  brown  fumes  of 
bromine  which  are  evolved. 


338  CHEMISTRY  AND   DAILY   LIFE 

EXPERIMENTS  TO  ACCOMPANY   CHAPTER  VII 

29.  Properties  of  sulphur.     Place  15  grams  of  roll  sul- 
phur, coarsely  pulverized,  in  a  test  tube  attached  to  a  test 
tube  holder,  and  heat  slowly  until  it  is  a  thin,  amber- colored 
liquid.     As  the  temperature  increases,  notice  that  the  liquid 
becomes  darker,  until  it  is  quite  dark  and  so  thick  and  viscid 
that  it  cannot  be  poured.     Continue  to  heat  until  the  material 
becomes  slightly  lighter  in  color  and  again  is  a  liquid.     Then 
quickly  pour  it  into  water,  and  when  cool  examine  the  mass 
and  describe  its  properties.     On  standing  several  days  it 
reverts  to  ordinary  sulphur.     Is  sulphur  soluble  in  water? 
Try  to  dissolve  some  roll  sulphur  in  carbon  bisulphide.     Pour 
off  the  clear  liquid  on  a  watch  glass  and  allow  it  to  stand  and 
evaporate  (no  flame  should  be  near).     Examine  the  crystals 
under  a  lens. 

30.  Sulphur   dioxide.     Fill  a  small  iron  spoon  half  full 
of  sulphur.     Ignite  the  sulphur  and  then  lower  it  into  a  small 
cylinder  containing  a  piece  of  wet,  colored  cloth,  a  piece  of  red 
litmus  paper,  or  a  red  carnation.     As  soon  as  the  sulphur 
stops  burning,  remove  the  spoon  and  cover  the  cylinder  with 
a  glass  plate.     What  is  the  effect  on  the  cloth,  on  the  litmus 
paper,  and  on  the  flower?     Sulphur  dioxide  destroys  organic 
coloring  matter  and  is  also  a  good  disinfectant.     It  kills  germ 
life. 

31.  Sulphuric  acid.     Make  the  following  tests  with  some 
of  the  sulphuric  acid  used  in  the  Babcock  test  for  milk  fat. 
(1)  Put  2  or  3  cc.  in  a  test  tube  and  stick  a  splinter  of  wood 
into  it  and  leave  it  there.     Then  remove  the  splinter.      Wash 
off  the  acid,  and  examine  the  stick.     It  has  turned  black. 
What  is  this  black  material  ?     Also  drop  a  piece  of  sugar, 
about  a  gram,  into  2  cc.  of  the  sulphuric  acid.     (2)  Put  10  cc. 
of  water  and  1  cc.  of  sulphuric  acid  into  a  test  tube ;  then  add 


PRACTICAL  LABORATORY  EXPERIMENTS   339 

2  to  3  cc.  of  barium  chloride  solution.  Observe  the  result. 
Barium  sulphate  has  been  formed.  This  is  a  very  insoluble 
precipitate,  and  this  test  is  a  general  one  for  sulphates.  (3) 
Let  the  barium  sulphate  settle,  pour  off  the  clear  supernatant 
liquid,  and  try  to  dissolve  the  white  salt  in  hot  hydrochloric 
acid.  Does  it  dissolve? 

32.  Hydrogen     sulphide.      Arrange     the     generator    as 
shown  in  Fig.  119.     The  delivery  tube  and  cork  should  fit 
tightly,  and  the  delivery  tube  should  pass  into  a  solution 
of  lead  nitrate.     Set  the  apparatus  under  a  hood.     Place  10 
grams  of  iron  sulphide  in  the  generator,  add  30  cc.  of  dilute 
hydrochloric  acid,  and  immediately  connect  with  the  delivery 
tube.     Note  the  precipitate  formed.     Pass  the  gas  into  a 
solution  of  common  salt,  then  into  a  solution  of  copper  sul- 
phate, then  into  a  solution  of  tartar  emetic.     Note  the  results. 
Note  the  odor  of  the  gas.     It  is  formed  when  organic  matter 
decomposes,  as  in  the  rotting  of  eggs  and  manure. 

33.  Test  for  phosphates.     In  a  50-cc.  beaker  on  a  sand 
bath,  dissolve  half  a  gram  of  bone  ash  in  10  cc.  of  dilute 
nitric  acid  and  20  cc.  of  water.     Filter,  and  to  the  filtrate 
add  5  cc.  of  ammonium  molybdate  solution  and  then  stir 
the  mixture.     Observe  the  yellow  precipitate,  which  is  ammo- 
nium  phosphomolybdate.     This  is  a  general  test  for  phos- 
phates.    It  should  always  be  made  in  a  faintly  acid  solution. 

34.  Insoluble    phosphates.      Dissolve    one-half    gram    of 
sodium  phosphate  in  10  cc.  of  distilled  water  and  then  add 
10  cc.  of  water  containing  half  a  gram  of  calcium  chloride 
in  solution.     Observe  the  result.     The  precipitate  is  calcium 
phosphate.     Repeat  the  experiment,  using  alum  instead  of 
calcium  chloride.     In  this  case  the  precipitate  is  aluminum 
phosphate. 


340  CHEMISTRY  AND   DAILY  LIFE 

EXPERIMENTS  TO  ACCOMPANY   CHAPTER  VIII 

35.  Making   boric  acid    from    borax.      Boil    100  cc.   of 
water  and  stir  in  powdered  borax  till  no  more  will  dissolve. 
Then  acidify  with  hydrochloric  acid.     On  cooling,  the  flakes 
of  boric  acid  separate   out.     Filter   off  and   test   the   solid 
residue  as  follows:    (1)  Dissolve  some  of  the  boric  acid  in 
5  cc.  of  water   contained  in  a  porcelain   evaporating  dish. 
Add  2  drops  of  sulphuric  acid  and  10  cc.  of  alcohol  to  the 
solution,  and  then  carefully  apply  the  flame  to  the  dish. 
When  the  alcohol  begins  to  evaporate,  ignite  it  with  the  flame. 
It  will  burn  with  a  green  flame  which  shows  the  presence 
of  boric  acid.     (2)  Test  some  of  the  aqueous  boric  acid  solu- 
tion with  turmeric  paper.     Note  the  color  produced.     The 
result  is  better  if  the  boric  acid  solution  is  acidified  with 
hydrochloric  acid  and  the  turmeric  paper  is  dried  at  100°  C. 
after  having  been  moistened  with  this  solution. 

36.  Insolubility    of    silicates.      Weigh    out    carefully    5 
grams  of  ordinary  soil  and  place  it  in  a  flask  and  add  25  cc. 
of     concentrated     hydrochloric     acid.     Does     it     dissolve? 
Warm  for  an  hour ;   pour  off  the  acid  through  a  filter  paper, 
and  wash  the  rest  of  the  soil  on  to  the  filter  paper.     Put  the 
funnel  containing  the  soil  in  a  warm  place  and  let  dry.     Then 
reweigh  the  residue  after  tapping  it  out  of  the  paper,  being 
careful  that  none  is  lost.     Has  the  acid  dissolved  very  much  ? 
The  soil  is  largely  made  up  of  silicates,  which  are  almost 
insoluble  materials. 

37.  Sodium  silicate.       Place  1  cc.   of  a   sirupy  solution 
of  sodium  water  glass  in  an  evaporating  dish,  dilute  with  10 
cc.  of  water,  and  add  2  to  3  cc.  of  concentrated  hydrochloric 
acid.     Note  the  gelatinous  precipitate.     Evaporate  to  dry- 
ness,  and  heat  the  dish  gently  over  a  low  flame.     Cool,  add 
water,  filter,  and  examine  the  solid  residue.     What  is  it  ? 


PRACTICAL   LABORATORY  EXPERIMENTS       341 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  IX 

38.  Preparation  of  carbon.      Place  2  pieces  of  wood  and 
a  piece  of  bone,  each  as  large  as  a  bean,  in  an  iron  crucible 
and  cover  the  materials  with  sand.     Heat  the  crucible  until 
smoking  ceases.      Remove  from  the  flame,  let  cool,  and  ex- 
amine the  charcoal  and  the  bone  black.     What  are  the  prin- 
cipal elements  in  wood?     In  bone?     Try  the  same  experi- 
ment with  some  ground  wheat.     Particles  of  carbon  may 
be  obtained  from  a  luminous  gas  flame  or  a  candle  or  lamp 
flame,   by  holding  a  piece  of  cold  porcelain  in  the  flame. 
Carbon  is  deposited  in  chimneys  as  soot  when  fuel  is  burned 
with  a  poor  draft.     When  fuel  is  burned  completely,  the 
carbon  disappears  entirely  as  the  gas,  carbon  dioxide. 

39.  Reducing  power  of  carbon.       Mix  thoroughly  from 
2  to  3  grams  of  pulverized  copper  oxide  and  an  equal  bulk 
of  pulverized  charcoal.     Place  the  mixture  in  a  small  test 
tube  and  apply  heat.     Observe  the  result.       What  is  the 
bright   red   material   produced?     What   causes   the  oxygen 
to  be  separated  from  the  copper  oxide  ? 

40.  Absorbing  power  of  carbon.       To   10  cc.  of   water 
in  a  test  tube  add  5  drops  of  cochineal  solution  and  10  cc. 
of  hydrogen  sulphide  water.     Add  3  to  5  grams  of  bone  black 
or  animal  charcoal.     Stopper  the   tube    with   a   cork  and 
shake  it.     Let  stand  5  minutes,  and  then  pour  upon  a  filter. 
Now  smell  of  the  liquid  and  look  at  the  color  of  the  fil- 
trate.    It  has  lost  its  color,  and  is  odorless.     The  charcoal 
absorbs  both  colors  and  odors.     A  half  bushel  of  charcoal 
in  a  bag  hung  in  the  water  of  a  cistern  will  gradually  remove 
the  odor  of  the  cistern  water. 

41.  Preparation  of  carbon  dioxide.      Arrange  the  appa- 
ratus as  shown  in  Fig.  119.     Put  20  grams  of  marble  in  the 
flask  and  sufficient  water  to  cover  the  end  of  the  thistle  tube. 


342  CHEMISTRY  AND   DAILY  LIFE 

Fill  2  or  3  cylinders  with  water  for  collecting  the  gas.  Then 
add  slowly  through  the  tube  30  cc.  of  concentrated  hydro- 
chloric acid.  Allow  some  of  the  fresh  gas  to  escape,  and  then 
collect  from  2  to  3  cylinders  of  the  gas.  Remove  the  cylin- 
ders, and  set  them  upright  on  the  table.  (1)  While  the  ap- 
paratus is  running  pass  some  of  the  gas  into  a  test  tube  of 
limewater,  and  note  the  result.  A  precipitate  is  first  formed 
and  gradually  then  redissolved.  Boil  the  clear  solution 
thus  formed  and  note  the  reappearance  of  the  precipitate. 

(2)  Test  some  of  the  escaping  gas  with  a  burning  splinter. 

(3)  Pour  a  cylinder  of  the  gas  over  a  candle  flame.      What 
happens?     (4)  Invert  another  cylinder  over  a  25  per  cent 
solution    of   sodium   hydroxide.      Why   does    the   gas   dis- 
appear ? 

Agricultural  students  may  also  perform  similar  experi- 
ments, using  other  calcium-containing  substances,  such  as 
caustic  lime,  limestone,  floats,  and  gypsum,  to  see  if  these 
contain  carbonic  acid,  as  does  marble. 

42.  Making  hard  soap.     In  a  beaker  dissolve  15  grams 
of  caustic  soda  in  120  cc.  of  water.     Pour  half  of  the  water 
into  a  porcelain  dish  of  about  500  cc.  capacity,  add  50  cc. 
of  water  and  50  grams  of  tallow.     Boil  the  solution  for  45 
minutes,  carefully  replacing  from  time  to  time  the  water 
lost  by  evaporation.     Then  add  the  remainder  of  the  caustic 
soda  and  boil  for  at  least  an  hour  more.     The  volume  of  the 
liquid  may  finally  be  allowed  to  decrease  about  one-third. 
Add  20  grams  of  common  salt,  boil  for  a  few  minutes,  and 
allow  to  cool.     The  soap  rises  to  the  top,  and  the  glycerine, 
excess  of  lye,  and  salt  remain  in  solution.     Try  to  make 
soap    similarly,    using   gas    engine    cylinder   oil    instead    of 
tallow. 

43.  Alcoholic   fermentation.     Weigh    10    grams    of   flour 
into  a  500-cc.  bottle,  add  50  cc.  of  water  and  a  small  piece 


PRACTICAL   LABORATORY   EXPERIMENTS       343 


FIG.  123. — Alcoholic  fermentation. 


of  a  yeast  cake.  By  means  of  a  delivery  tube  connect 
the  flask  with  a  test  tube  containing  enough  clear  limewater 
to  cover  the  end  of  the  tube  (see  Fig.  123).  Cover  the  lime- 
water  with  one- 
quarter  of  an 
inch  of  kerosene. 
Why?  Place  the 
bottle  on  a  warm 
sand  bath  (not 
over  85°  F.)  for 
half  an  hour. 
Why?  Observe 
the  bubbles  of  gas 
given  off  and  the 


precipitate  that  is 
formed  in  the  lime- 
water.     Carbon    dioxide  and  alcohol  are  formed.     This  is 
what  occurs  in  bread  making. 

44.  Removal  of  grease  spots  from  clothing.     Spots  due  to 
fats  such  as  butter,  tallow,  olive  oil,  etc.,  can  be  removed 
with  soap  or  with  gasoline  or  benzine ;   also  by  placing  the 
fabric  between  blotting  paper  and  applying  a  warm  iron.     Try 
the  solubility  of  fats  in  gasoline  or  benzine,  also  the  removal 
of  a  grease  spot  by  the  hot  iron  method.     Grease  may  also 
be  removed  by  ammonia  water  or  even  a  solution  of  borax. 
In  the  case  of  spots  due  to  mineral  oils,  the  spot  should  first 
be  treated,  or  softened  with  some  oil  and  then  treated  with 
gasoline.     Why?     Gasoline  is  inflammable.     Do  not   have 
flames  around  when  you  are  using  it. 

45.  Washing    soda.     This   is    sodium  carbonate  and    is 
sometimes  used  as  a  filler  for  soap.     It  is  the  main  constitu- 
ent of  washing  powders.     To  test  such  a  powder  for  sodium 
carbonate,  put  5  grams  in  a  test  tube  and  add  a  few  drops 


344  CHEMISTRY  AND   DAILY  LIFE 

of  hydrochloric  acid.     If  there  is  a  brisk  evolution  of  gas,  it 
indicates  the  presence  of  a  carbonate. 

46.  Odors  and    appearance  of    some  important    organic 
compounds.     The  instructor  should  have  the  student  ex- 
amine with  the  eye  and  nose  the  following  materials :    car- 
bolic acid,  ether,  banana  oil,  carbon  tetrachloride,  chloro- 
form, etc. 

47.  Test   for   nitrogenous    organic   compounds.     Mix    a 
gram  of  dry  clover  hay,  peas,  or  meat  with  enough  soda- 
lime  to  half  fill  a  test  tube.     Connect  the  test  tube  with  a 
delivery  tube  as  in  Fig.  120,  but  let  the  end  of  the  tube  lead 
into  another  test  tube  containing  water.     Apply  heat  for  from 
5  to  10  minutes.     Test  the  water  with  red  litmus  paper. 
It  should  turn  blue.     Soda-lime  decomposes  protein  material 
and  liberates  nitrogen  as  ammonia.     The  carbon  and  oxygen 
of  the  protein  unite  and  form  carbon  dioxide  and  water; 
the    carbon    dioxide     forms    carbonates    with    the    soda- 
lime. 

48.  Test  for  proteins.     Make  about  a  10  per  cent  caustic 
potash  solution  by  dissolving  5  grams  of  caustic  potash  in 
45  cc.  of  water.     In  another  glass  dissolve  a  piece  of  copper 
sulphate  (bluestone)  the  size  of   a   pea  in  50  cc.  of  water. 
Pour  about  one-fifth  of  the  white  of  an  egg  into  50  cc.  of 
water.     Place  10  cc.  of  this  egg  solution  in  a  test  tube,  add 
5  cc.  of  the  potash  solution,  put  the  thumb  over  the  tube,  and 
shake  until  all  is  well  mixed.     Now  add  a  few  drops  of  the 
copper  sulphate  solution  and  shake  again.     At  first  the  only 
color  will  be  a  greenish  blue,  but  on  standing  this  will  change 
to  a  deep  violet  color.     This  is  the  test  for  proteins.     Test 
wheat,  corn,  bran,  and  meat  by  this  means.     These  materials 
should  be  crushed  or  ground,  and  warmed  for  a  short  time 
in  a  little  of  the  caustic  potash  solution  and  then  filtered  before 
adding  the  copper  sulphate  solution. 


PRACTICAL  LABORATORY  EXPERIMENTS      345 

49.  Preparation  of   a  protein.     Put  about   25   grams  of 
flour  in  a  porcelain  dish,  add  12  to  15  cc.  of  water,  and  mix 
into  a  stiff  dough.     Do  not  have  too  much  water  present. 
Let  stand  one-half  hour,  remove  the  ball  of  dough,  and,  hold- 
ing it  in  the  fingers,  add  water  little  by  little  and  so  wash 
out  the  starch  by  further  manipulation  with  the  fingers. 
Continue  the  washing  until  the  liquid  runs  clear,  and  then 
place  the  ball  of  gluten  in  water  for  one-half  hour.     Remove 
it  from  the  water,  freeing  it  from  water  as  much  as  possible, 
and  then  weigh  it.     Spread  it  out  in  a  thin  cake,  and  then 
let  it  dry  in  the  oven  or  in  a  warm  place,  and  finally  reweigh 
it.     Calculate  the  per  cent  of  gluten  in  the  flour.     The  gluten 
consists  of  the  two  principal  proteins  of  the  wheat. 

50.  Fats  and  oils.     Crush  5  grams  of  flax  or  hemp  seed 
on  a  piece  of  white  paper.     A  grease  spot  will  appear  on  the 
latter.     Should  the  test   fail  to  show  oil,  place  the  crushed 
seeds  and  the  paper  in  a  warm  place  on  a  tin  plate.     The 
higher  temperature  will  melt  the  oil  out,  which  will  then  be 
shown  by  the  grease  spot  on  the  paper. 

51.  Fats  and   oils.     Crush  four  or  five   kernels  of   corn. 
Place  the  powder  in  a  flask,  and  pour  over  it  25  cc.  of  gasoline. 
Shake  it  at  intervals  for  15  minutes.     Keep  the  flask  loosely 
stoppered  and  away  from  flames.     Then  pour  the  gasoline 
off,  and  through  a  filter  paper,  catching  the  filtrate  in  a 
beaker.     Allow  the  gasoline  to  evaporate  slowly.     A  resi- 
due  is   left   in   the   beaker.     Test   it   between   the  fingers 
for  its  greasy  feeling.     Gasoline  and  benzine  dissolve  fats. 
Grease  spots  on  cloth  are  removed  by  washing  with  gaso- 
line or  benzine. 

52.  Preparation   of   starch.     Make  a  pulp  of   two  clean 
potatoes.     Tie  the  pulp  in  a  cloth  and  squeeze  the  juice 
into  a  beaker  filled  with  water,  occasionally  dipping  the  bag 
into  water.     Allow  the  beaker  to  stand  for  20  minutes,  or 


346  CHEMISTRY  AND   DAILY  LIFE 

until*  the  starch  has  settled.  Now  pour  off  the  water,  and 
if  the  starch  is  not  clean,  wash  it  by  adding  more  water  and 
again  allowing  it  to  settle.  Finally  pour  off  the  water.  Leave 
the  beaker  in  the  desk  until  the  starch  is  dry,  and  then  save 
the  starch  for  the  following  tests. 

53.  Test  for  starch.     Taste  some  of  the   starch.     It  is 
practically  tasteless.      Place  one-half  gram  in  a  test  tube 
about  half  full  of  water.  •   Shake  the  test  tube,  then  boil, 
and  filter.     To  the  filtrate  add  a  few  drops  of  iodine  solution. 
(This  is  made  by  dissolving  5  grams  of  potassium  iodide 
in  50  cc.  of  water  and  then  adding  1  gram  of  iodine  to  the 
solution.)     A  deep  blue  color  appears  throughout  the  solution. 
Treat  some  of  the  starch  with  cold  water,  but  do  not  filter ; 
add  some  of  the  iodine  solution.     On  standing,  the  starch, 
settling  out  at  the  bottom,  will  be  blue.     In  the  first*  case 
the  starch  was  in  solution,  in  the  second  it  was  not.     Prep- 
arations of  starch  for  the  iodine  test  may  also  be  made  from 
corn,  wheat,  oats,  or  beans. 

54.  Test  for  sugar  (glucose).     Grind  25  grams  of  dried 
raisins  in  50  cc.  of  water.     Filter  the  solution  into  a  beaker. 
Into  a  test  tube  place  10  cc.  of  Fehling's  solution.     This  is 
made  by  dissolving  6.2  grams  of  copper  sulphate,  3.5  grams 
of  Rochelle  salts  (sodium  potassium  tartrate) ,  and  2  grams  of 
potassium  hydroxide  in  100  cc.  of  water.     Place  about  10  cc. 
of  the  Fehling's  solution  in  a  test  tube  and  add  from  5  to  10 
cc.  of  the  raisin  solution.    Heat  over  a  flame  and  let  the  liquid 
boil  a  few  seconds.    A  reddish  brown  precipitate  forms,  which 
on  standing  deposits  on  the  bottom  of  the  test  tube.     This 
precipitate  is  the  red  oxide  of  copper,  Cu2O,  and  shows  the 
presence  of  glucose  in  the  solution.     Test  the  water  extract 
from  corn  or  wheat  for  glucose  ;  also  the  extract  of  an  apple, 
a  sample  of  honey,  and  one  of  "Karo  sirup." 


PRACTICAL  LABORATORY  EXPERIMENTS        347 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  X 

55.  Preparation    of    potassium    hydroxide.     Dissolve    5 
grams  of  potassium  carbonate  or  wood  ashes  in  15  cc.  of 
water  in  an  evaporating  dish.     Add  a  mixture  of  3  grams  of 
barium  hydroxide  (also  called   barium  hydrate)  and  10  cc. 
of  water.     Heat  on  a  sand  bath  for  5  minutes.     Filter  off 
the  solution  and  observe  the  precipitate.     Evaporate  some 
of  the  filtrate  to  dry  ness  by  heating  on  the  sand  bath.     This 
is  potassium  hydroxide.     Keep  it  for  experiment  56.     Wood 
ashes  contain  potassium  carbonate  and  are  often  the  source  of 
the  "  lye  "  used  in  soap  making  on  the  farm. 

56.  Test  for  potassium.     Dip  a  clean  platinum  wire  into  a 
solution  of  the  residue  left  from  the  last  experiment.     Hold 
it  in  a  non-luminous  Bunsen  flame  and  observe  the  flame 
through  a  blue  glass.     A  violet  color  shows  the  presence  of 
potassium.     If  no  platinum  wire  is  at  hand,  use  a  clean  strip 
of  asbestos  paper.     Hold  a  crystal  of  potassium  chlorate  in 
the  flame  with  the  forceps. 

57.  Test  for  sodium.     Dip  a  clean  platinum  wire  into  a 
solution  of  common  salt;    hold  it  in  the  Bunsen  flame  and 
observe  the  bright  yellow  color  imparted  to  the  flame.     This 
is  a  test  for  sodium.     Try  the  same  test  by  holding  a  piece 
of  rock  salt  in  the  flame  with  a  forceps. 

58.  Precipitation  of   barium  sulphate.     To  a  solution  of 
barium  chloride  add  a  drop  of  sulphuric  acid.     Note  the 
heavy  white  precipitate  formed,  which  is  the  insoluble  barium 
sulphate.     To  a  solution  of  copper  sulphate  add  a  few  drops 
of  barium  chloride.     Here  again  the  insoluble  barium  sul- 
phate is  formed. 

59.  Tests  for   the  alkaline  earth  metals.     Using  a  clean 
forceps,  hold  a  piece  of  a  salt  of  strontium  in  the  flame  and 
note   the  color  produced.     Perform   the  same  experiment, 


348  •   CHEMISTRY  AND  DAILY  LIFE 

holding  a  piece  of  a  calcium  salt  in  the  flame ;  also  repeat  the 
experiment  with  a  piece  of  a  barium  salt. 

60.  Testing  the  quality  of   lime.     Place  about  40  grams 
of  burned  lime  in  an  evaporating  dish,  and  moisten  it  well 
with  water,  warming  to  about  35°  C.  to  hasten  the  action, 
if  necessary.     Note  the  reaction  and  observe  how  the  mass 
warms  up.     Good,  fresh  lime  readily  undergoes  the  slaking 
process.     Place  some  of  the  slaked   lime  in  a   bottle;   add 
100  cc.  of  distilled  water ;  shake  vigorously,  and  allow  to  stand 
for  four  or  five  hours.     Then  filter  some  of  the  solution  and 
test  it  by  blowing  air  through  it,  using  a  glass  tube.     Place 
about  one-half  gram  of  the  slaked  lime  in  a  test  tube,  add 
10  cc.  of  water  and  then  a  few  drops  of  hydrochloric  acid. 
When  the  action  ceases,  add  more  acid,  a  little  at  a  time,  and 
warm.     What  has  not  dissolved  consists  of  silica  and  clay. 
Lime  of  high  purity  contains  less  than  10  per  cent  of  acid- 
insoluble  material. 

61.  Plaster  of    Paris.     In    a    test    tube  carefully  heat 
10  grams  of   powdered  gypsum  to  115°  C.     Regulate  the 
temperature  by  means  of  a  thermometer  so  that  it  reaches 
no  higher  than    115°   C.     WThy?     Allow  it  to   cool.     Mix 
with  a  small  quantity  of  water  and  note  that  in  a  few  min- 
utes the  mass  becomes  hard.     Explain. 

62.  Burning  magnesium.     Hold   a   piece  of   magnesium 
ribbon  about  an  inch  long  in  a  forceps  and  apply  a  lighted 
match.     The   ribbon   burns   with   a   brilliant   white   flame. 
Examine  the  white  product  formed.     What  is  it?     Flash- 
light powder  consists  of  about  5  parts  of  powdered  magnesium 
to  9  parts  of  potassium  chlorate.     It  should  be  used  with 
care. 


PRACTICAL  LABORATORY  EXPERIMENTS   349 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XI 

63.  Testing  for  alum.     Add  a  few  drops  of  an  alum  solu- 
tion to  a  test  tube  containing  5  cc.  of  water  and  then  add  a 
few  drops  of  logwood  extract  and  2  cc.  of  ammonium  car- 
bonate solution.     Observe  the  result.     Mix  about  2  grams 
of  flour  in  a  dish  with  water  containing  a  few  drops  of  alum 
solution.     Add  a  few  drops  of  logwood  extract  and  the  same 
amount  of  ammonium    carbonate  solution.     Mix  well  and 
observe  the  result.     Repeat  the  test,  using  a  baking  powder, 
testing  for  the  presence  or  absence  of  alum.     In  the  presence 
of  alum  a  blue  color  is  always  obtained  with  tincture  of  log- 
wood and  ammonium  carbonate  solution. 

64.  Compounds  of  alum  and  protein.     To  5  cc.  of  a  solu- 
tion of  egg  white  add  a  few  drops  of  an  alum  solution  and 
observe  the  result.     A  heavy  precipitate  will  form.     This 
is  an  insoluble  compound  of  protein  and  alum.     To  a  solu- 
tion of  aluminum  chloride  add  ammonia  water.     The  same 
result  is  noticed,  but  in  this  case  aluminum  hydroxide  is 
formed. 

65.  Copper  in  a   silver  coin.     Under    a    hood,   dissolve 
about  one-fourth  of  a  dime  in  dilute  nitric  acid.     It  is  best 
to  hammer  out  the  coin  and  then  cut  it.     Account  for  the 
bluish  color  of  the  solution.     To  the  solution  add  a  solution 
of  hydrochloric  acid  until  no  further  precipitate  is  formed. 
The  white  precipitate  is  silver  chloride.     Filter  and  evapo- 
rate the  blue  solution  of  copper  nitrate  in  an  evaporating 
dish,  finally  igniting  to  redness  over  a  flame.     The  black 
residue  is  the  oxide  of  copper.     Expose  the  silver  chloride 
to  the  light.     What  happens? 

66.  Copper  and   its  reactions.     (1)  Dissolve  5  grams  of 
copper  sulphate  in  100  cc.  of  water.     Place  a  bright  iron  nail 
in  the  solution  and  note   the  result.     (2)   To  5  grams  of 


350  CHEMISTRY  AND   DAILY  LIFE 

Rochelle  salts  add  10  cc.  of  water,  and  5  cc.  of  concentrated 
caustic  soda  solution,  after  all  the  salt  has  dissolved.  Now 
add  5  cc.  of  the  copper  sulphate  solution  and  then  treat  the 
resulting  solution  with  1  cc.  of  glucose  ("  Karo  sirup  ")  and  boil. 
A  reddish  brown  precipitate  of  cuprous  oxide,  Cu20,  is  formed. 
This  is  the  test  for  sugar.  (3)  To  10  cc.  of  the  copper  sul- 
phate solution  add  a  few  drops  of  potassium  ferrocyanide. 
A  reddish  brown  precipitate  is  formed.  This  is  a  delicate 
test  for  copper,  and  can  be  used  for  testing  Bordeaux  mix- 
ture for  excess  of  copper  sulphate  in  solution.  In  Bordeaux 
preparation,  if  this  test  shows  the  brown  precipitate,  more 
lime  must  be  added ;  see  experiment  151. 

67.  Copper  in  brass.     Under  the  hood,  treat  about  0.2 
gram  of  brass  with  5  cc.  of  nitric  acid  in  a  test  tube  and  note 
the  blue  color  of  the  solution.     This  color  is  due  to  the  for- 
mation of  copper  nitrate. 

68.  An  antidote  for  mercury  poisoning.     To   20   cc.   of 
water  add  5  or  6  drops  of  the  white  of  an  egg.     Stir  thor- 
oughly and  then  add  to  this  solution  a  few  cubic  centimeters 
of  a  dilute  solution  of  mercuric  chloride  (corrosive  sublimate), 
1  in  2000.     The  precipitate  is  a  compound  of  the  protein  and 
mercury.     In  case  of  mercury  poisoning  the  whites  of  eggs  and 
milk  are  a  good  antidote. 

69.  Preparation  of  mercury.     To  5  cc.  of  a  solution  of 
stannous  chloride  add  a  few  drops  of  a  solution  of  mercuric 
chloride.     The  gray  precipitate  that  separates  is  metallic 
mercury.     Note  the  physical  properties  of  some  mercury 
contained  in  a  bottle  on  the  reagent  shelf. 

70.  Lead  and  its  salts.     Dissolve  5  grams  of  metallic  lead 
in  warm,  dilute  nitric  acid.     Evaporate  off  nearly  all  of  the 
excess  of  acid  and  allow  the  liquid  to  stand  and  cool.    Pour  off 
the  remaining  liquid  from  the  crystals  and  dissolve  these  in 
50  cc.  of  water.     Test  separate  portions  of  5  cc.  each  of  this 


PRACTICAL  LABORATORY  EXPERIMENTS       351 

solution  with  (a)  hydrogen  sulphide;  (6)  dilute  sulphuric 
acid;  and  (c)  dilute  hydrochloric  acid.  Precipitates  of  dif- 
ferent colors  are  formed.  Lead  sulphide  is  black;  lead 
sulphate  and  chloride  are  white. 

71.  Action  of  water  on  lead.  «  Put  a  gram  of  clean  bright 
lead  shavings  into  a  test  tube  containing  10  cc.  of  distilled 
water.     After  24  hours  decant  the  clear  liquid  into  a  second 
tube.     Slightly  acidify  with  hydrochloric  acid  and  then  add 
5  to  10  cc.  of  fresh  hydrogen  sulphide  water.     A  black  or 
brown   coloration   indicates   lead   in   solution.     Soft  water, 
especially  peaty  water,  attacks  and  dissolves  lead  more  than 
does  hard  water.     In  contact  with  hard  water  the  lead  be- 
comes coated  with  the  insoluble  lead  sulphate  and  carbonate 
of   lime   which    protect    the  metallic  surface  from  further 
attack. 

72.  Preparation  of  lead  chromate.     To  5  cc.  of  a  solution 
of  potassium  dichromate  add  3  cc.  of  lead  acetate  (sugar  of 
lead)  solution.     The  beautiful  yellow  precipitate  formed  is 
chrome  yellow,  or  lead  chromate,  which  is  used  as  a  pigment 
in  paints. 

73.  Making  formalin.     Treat  10  to  20  cc.  of  wood  alcohol 
with  one-half  gram  of  potassium  permanganate  and  1  to  2 
drops  of  strong  sulphuric  acid.     Heat  the  beaker  gently. 
Note  the  odor  produced.     The  penetrating  smell  is  due  to 
the   production   of   formaldehyde,    formed   from   the   wood 
alcohol  by  oxidation  of  the  latter  by  the  permanganate. 

74.  Cobalt  bead.     In  a  loop  of  platinum  wire,  made  by 
bending  the  wire  around  the  sharp  end  of  a  pencil,  place  some 
borax  and  then  fuse  it  in  the  flame.     Note  the  color  of  the 
bead.     Now  dip  the  bead  into  a  dilute  solution  of  cobalt 
nitrate.     Then  put  the  loop  with  the  bead  into  the  flame 
again  and  allow   the  bead   to  melt.      Note  the   beautiful 
blue  color  of  the  bead  on  cooling. 


352  CHEMISTRY  AND   DAILY  LIFE 

75.  Preparation  of  iron  sulphate.     Place  25  grams  of  iron 
nails  in  a  500-cc.  flask,  add  about  25  cc.  of  dilute  sulphuric 
acid  (1  part  acid  to  5  parts  water),  warm  gently  until  no 
more  gas  comes  off.     Pour  the  clear  solution  into  a  clean 
beaker.     Add  2  to  3  cc.  of  dilute  sulphuric  acid  to  the  solu- 
tion, boil  the  liquid  down  to  one-half  of  its  volume,  and  allow 
it  to  cool.     Crystals  of  iron  sulphate  will  separate  out.     The 
liquid  should  be  poured  off  and  the  crystals  allowed  to  drain. 
This  is  the  material  used  in  the  destruction  of  weeds  and  is 
commonly  prepared  at  steel  plate  mills.     Other  names  for 
this  salt  are  copperas,  green  vitriol,  and  ferrous  sulphate. 

76.  Change  of  ferrous  to  ferric  iron.     Dissolve  one-half 
gram  of  ferrous  sulphate  in  20  cc.  of  water.     Divide  the  liquid 
into  two  equal  portions.     To  the  first  portion  add  a  few  drops 
of  ammonia  water  until  a  precipitate  is  obtained.     To  the 
other  portion  add  five  drops  of  concentrated  nitric  acid. 
Heat  this  latter  portion  to  boiling;  cool,  and  then  add  am- 
monia water  until  a  precipitate  forms.     Compare  the  two 
precipitates.     The  nitric  acid  oxidizes  the  iron,  which  then  is 
in  a  substance  containing  more  oxygen.     The  copperas  is  fer- 
rous sulphate ;  by  oxidizing  it  with  nitric  acid  it  was  changed 
to  ferric  sulphate. 

77.  Compounds  of  tannin  and  iron  (ink).     (1)    Dissolve 
1  gram  of  tannic  acid  in  25  cc.  of  hot  water.     Dip  a  piece 
of   cotton   cloth    (about   3   by   10  cm.)   into    the    solution. 
Dry  the  cloth,  and    then  dip  it  into  a  solution  of   ferrous 
sulphate  (1  gram  in  25  cc.  of  water).     After  the  cloth  has 
dried,  see  if  the  color  can  be  removed  by  washing.     (2)  Add 
5  cc.  of  ferrous  sulphate  solution  to  5  cc.  of  tannic  acid  solu- 
tion.    Observe  the  result.     Does  it  look  like  ink  ? 

78.  Making  a  blue  print.     Place  a  leaf  or  a  drawing  made 
on  thin  paper  on  the  glass  of  a  photographer's  printing  frame 
and  then  cover  it  with  a  piece  of  blue  printing  paper  (the 


PRACTICAL  LABORATORY  EXPERIMENTS      353 

sensitive  side  next  to  the  leaf).  This  paper  can  be  secured 
at  most  drug  stores.  The  operation  of  placing  the  object  and 
paper  together  should  be  done  in  a  darkened  room.  Now 
expose  the  printing  frame  to  direct  sunlight  for  about  3  to  5 
minutes.  Several  trials  must  be  made  to  determine  the 
time  of  exposure  necessary  for  a  successful  print.  Remove 
the  paper  from  the  frame.  Wash  with  water  and  spread 
the  print  on  a  cloth  to  dry. 

EXPERIMENTS  TO   ACCOMPANY  CHAPTER  XII 

79.  Drying  of  linseed  oil.     With  a  brush  spread  a  layer 
of  linseed  oil  (very  thin)  on  a  well-varnished  ruler  and  allow 
it  to  stand  several  days.     Now  examine  it.     Has  it  set  to  a 
hard  film?     Crush  10  grams  of  flaxseed  in  a  mortar.     Ex- 
tract the  material  with  gasoline  in  a  flask.     Pour  off  the 
gasoline,  and  out  of  doors,  or  under  a  hood,  allow  the  gaso- 
line to  evaporate   off.     Paint  the  ruler  with  the  oil  that 
is  left.     Try  a  film  of  corn  oil  on  a  ruler.     How  does  it  act? 

80.  Solubility  of  oils.     Try  to  dissolve  some  linseed  oil  in 
gasoline;    also  in  carbon  bisulphide.     Try  the  same  experi- 
ment, using  corn  oil,  also  butter  fat,  instead  of  linseed  oil. 

EXPERIMENTS  TO   ACCOMPANY  CHAPTER  XIII 

81.  Odor  of  burning  wool  and  cotton.     Burn  small  pieces 
of  wool,  silk,  and  horse's  hoof  and  note  the  odor  in  each  case. 
Try  the  same  experiment  with  cotton.     The  former  materials 
are  nitrogenous  and  give  rise  to  ammonia  and  other  odorifer- 
ous nitrogenous  compounds,  while  cotton  does  not.     Try  the 
solubility  of  the  various  materials  mentioned  above  in  am- 
monia water.     Wool,  silk,  and  horn  will  dissolve,  while  cot- 
ton will  not. 

2  A 


354  CHEMISTRY  AND   DAILY  LIFE 

82.  Bluing.     Indigo  was  very  generally  used  for  bluing  in 
the  laundry.     Another  material  is  now  commonly  employed  ; 
namely,  Prussian  blue.     This  is  ferric  ferrocyanide,  a  complex 
cyanide  of  iron.     Because  of  the  ease  with  which  it  decom- 
poses with  alkalies,  there  is  danger  that  iron  rust  may  be 
deposited  on  the  goods  if  this  form  of  bluing  is  used.     To 
10  cc.  of  a  10  per  cent  solution  of  ferric  chloride,  add  5  cc.  of 
a  10  per  cent  solution  of  potassium  ferrocyanide,  and  about 
5  drops  of  hydrochloric  acid.     The  blue  precipitate  is  Prus- 
sian blue.     Now  add  an  excess  of  caustic  alkali  and  heat  to 
boiling.     Note  the  reddish  brown  precipitate  of  ferric  hy- 
droxide.    This  is  what  causes  the  iron  rust  stains. 

83.  Dyeing  cloth.     Dip  strips  of  white  woolen,  silk,  and 
cotton  cloth  into  a  solution  of  fuchsine.     After  immersion 
in  the  solution  remove  the  strips  and  allow  them  to  drain. 
When  they  are  nearly  .dry  they  may  be  washed  in  water  to 
test  the  fastness  of  the  color  on  the  various  fabrics. 

84.  Gelatine  in  sole  leather.     A  piece  of  sole  leather,  half 
as  large  as  the  hand,  should  be  boiled  in  water  for  an  hour  and 
then  allowed  to  cool.     Does  the  solution  gelatinize  or  become 
viscid  and  sticky?     Sole  leather  has  been  treated  in  such  a 
way  that  it  contains  no  gelatine.     Try  the  same  experiment, 
using  a  piece  of  fresh  cowhide.     Note  the  result. 

85.  Solubility  of  rubber.     Place  about  0.5  gram  of  rubber 
in  a  test  tube,  add  5  cc.  of  carbon  bisulphide,  heat  gently  in 
a  hot  water  bath,  and  shake  the  contents  of  the  tube.     What 
happens?     Notice   how   the   rubber   swells   up   and   slowly 
dissolves.     No  flame  should  be  near. 

86.  Solubility  of  asphalt.      Dissolve  some  asphalt  paint 
in  turpentine  and  apply  it  to  a  piece  of  unpainted  wood. 
Set  the  wood  aside  to  dry  and  note  the  stain  left  behind. 

87.  Removal  of  iron  rust  from  cloth.     Stretch  the  stained 
cloth  over -a  dish  containing  hot  water.     Then  as  the  steam 


PRACTICAL  LABORATORY  EXPERIMENTS      355 

rises  and  the  cloth  becomes  moist,  drop  a  few  drops  of  dilute 
(10  per  cent)  hydrochloric  acid  or,  better,  10  per  cent  oxalic 
acid  upon  the  rust  spot,  preferably  with  a  medicine  dropper. 
When  oxalic  is  used  the  fabric  may  be  immersed  directly 
in  the  acid.  After  a  moment,  lower  the  fabric  into  the  water. 
If  the  spot  is  not  removed,  repeat  the  operation.  Then  rinse 
in  clear  water  and  finally  in  dilute  ammonia  water  to  neutral- 
ize any  remaining  acid.  Then  rinse  again.  Iron  rust 
stains  may  often  be  completely  removed  from  fabrics  by 
means  of  lemon  juice. 

88.  Removal  of  paint  stains.     These  can  be  removed  by 
the  use  of  turpentine.     Spot  some  cloth  with  paint  and,  after 
it  is  thoroughly  dried,  remove  the  stain  with  turpentine. 

89.  Removal  of  ink  stains.     A  great  many  ink  stains  can 
be  removed  with  sour  milk  or  with  some  dilute  acid  such  as 
oxalic  or  citric  acid.    If  the  ink  is  an  iron  tannate,  the  methods 
of  removing  iron  rust  will  be  applicable.     Stain  some  cloth 
with  ink,  and  then  remove  the  spot  with  the  reagents  men- 
tioned.    These  should  be  used  in  dilute  solution  (5  to  10  per 
cent) ;  and  after  application  and  removal  of  the  stain  the 
fabric  should  be  well  washed  with  water.     Long  contact  with 
the  acid  may  weaken  the  fabric. 

90.  Removal  of  fruit  stains.      Fruit  stains  may  be  re- 
moved from  many  fabrics  by  washing  in  water  containing 
a  little  borax  or  ammonia.     Always  try  this  treatment  first, 
as  it  will  not  injure  the  colors.     If  the  above  does  not  remove 
the  stain,  try  a  very  dilute  solution  of  chloride  of  lime  con- 
taining a  few  drops  of  dilute  acetic  acid  (vinegar).     When 
the  stains  have  been  removed,  wash  the  fabric  thoroughly 
with  clean  water.     In  the  case  of  wool  or  silk,  treatment  with 
soap  (care)  and  water  is  the  only  way.     If  not  effective,  the 
fabric  must  be  re-dyed.     Try  these  tests,  and  also  the  action 
of  ammonia  on  wool  and  silk. 


356  CHEMISTRY  AND  DAILY  LIFE 

91.  Coffee  and  tea  stains.      These  are  removed  in  the 
same  manner  as  the  fruit  stains.     They  are  due  to  the  color- 
ing matter  in  the  liquids.     Grass  stains  owe  their  color  to 
chlorophyll.     This  is  soluble  in  ammonia  water  or  in  alcohol, 
and  can  therefore  be  removed    from  fabrics  by  these    re- 
agents.    Apply   these    reagents   to    such    stains.     Also    try 
leaving  the  stained  material  in  the  sunlight.     What  is  the 
result? 

92.  Blood  stains.     These  are  due  to  the  red  pigment  of 
the    blood    called    haemoglobin.      This    coloring    matter    is 
easily  decomposed  by  acids.     It  is  also  soluble  in  warm  water, 
which  should  be  tried  for  the  removal  of  the  stain,  before 
using  the  acid  treatment. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XIV 

93.  Nitrogen  in  soil.     Mix  5  grams  of   soil  and  an  equal 
bulk  of  soda-lime  in  a  mortar  and  transfer  the  mixture  to  a 
strong  test  tube.     Connect  the  tube  with  a  delivery  tube 
as  in  Fig.  120,  but  have  the  end  of  the  tube  lead  into  another 
test  tube  containing  distilled  water.     Heat  the  first  test  tube 
cautiously  with  a  burner  for  five  to  ten  minutes.     Test  the 
water  with  litmus  paper  and  note  the  reaction.     The  soda- 
lime,  aided  by  heat,  decomposes  the  organic  matter  of  the 
soil  and  forms  water,  carbon  dioxide,  and  ammonia.     The 
latter  contains  the  nitrogen  and  has  passed  over  into  the 
water. 

94.  Phosphorus  in  soils.     Place  10  grams  of  soil  in  a  flask, 
add  25  cc.  strong  hydrochloric  acid,  and  warm  on  a  water 
bath  for  half  an  hour.     Pour  off  the  acid,  cool,  and  add  am- 
monia gradually,  shaking  after  each  addition,  and  continue 
this  until  the  solution  turns  red  litmus  blue.     Then  add 
nitric  acid  drop  by  drop  until  the  solution  is  slightly  acid, 


PRACTICAL  LABORATORY  EXPERIMENTS       357 

or  until  the  blue  litmus  becomes  red.  Then  add  10  cc.  of 
ammonium  molybdate  solution.  A  yellow  color  or  precipi- 
tate after  a  few  minutes  shows  the  presence  of  phosphorus. 
It  is  best  to  keep  the  solution  at  65°  C.  to  aid  the  precipita- 
tion of  the  ammonium  phosphomolybdate. 

95.  Reaction  of  soils.     For  this  experiment  use  (1)  peat, 
(2)  a  mildly  alkaline  soil,  and  (3)  a  clay  soil.     Bring  in  con- 
tact with  each  soil,  moistened  with  distilled  water,  pieces 
of  sensitive  red  and  blue  litmus  paper.     Note  any  changes 
in  color  of  the  litmus  paper  and  record  what  results  you  find. 
In  a  similar  way  test  the  soils  from  the  fields  of  your  own 
farm. 

96.  Correcting  the  acidity.     When  you  find  an  acid  soil, 
-  that  is  one  which  changes  blue  litmus  to  red,  —  take  a 

wash  basin  full  of  it  and  add  15  to  25  grams  of  burned  lime 
or  ground  limestone.  Stir  the  mixture  thoroughly  and 
test  it  again.  Try  the  same  experiment,  using  wood  ashes 
instead  of  lime.  If  the  soil  is  still  acid,  add  enough  lime  un- 
til it  shows  a  blue  color  with  litmus.  An  alkaline  or  "  sweet 
soil "  is  the  normal  one  for  most  agricultural  plants. 

97.  Weathering  of   limestone.      Place    about   25  grams 
each  of  fresh  limestone,  rotten  limestone,  and  residual  lime- 
stone soil  in  separate  beakers.     Add  100  cc.  of  5  per  cent 
hydrochloric  acid  to  each,  and  allow  them  to  stand  for  one 
hour.     Filter  off  the  insoluble  material  on  filter  papers  al- 
ready dried  and  of  known  weight.     Wash  the  residues  with 
water.     Dry  them  in  the  oven  at  100°  C.  and  weigh.     Cal- 
culate the  per  cent  of  insoluble  matter  in  each  case  and  ex- 
plain the  results. 

98.  Puddling  of  clay.      In  each  of  two  basins  place  a 
pound  of  dry  clay  soil.     To  one  of  these  add  water  until  the 
soil  is  slightly  moist,  but  do  not  work  or  stir  it.     To  the  other 
add  enough  water  to  make  the  clay  sticky;  mix  thoroughly 


358 


CHEMISTRY  AND   DAILY  LIFE 


with  a  stick  and  place  the  mixture  in  the  sun  to  dry.     Note 
the  results. 

99.  Effect  of  soluble  salts  on  soils.  To  20  pounds  of 
soil  in  a  box,  add  25  grams  of  sodium  nitrate  and  mix  thor- 
oughly. To  another  box  of  the  same  soil  add  2  grams  of 
the  same  salt  and  mix.  Water  both,  and  set  them  in  a  proper 
place  for  growth.  Plant  with  the  same  number  of  seeds  (25) 
and  after  the  plants  are  well  started  thin  to  the  same  number 
(12).  Note  the  results.  Too  much  of  soluble  salts  may  be 
harmful.  An  acre  of  soil  6  inches  deep  weighs  about  2,000,000 
pounds;  estimate  the  application  per  acre  on  the  above 
amounts  of  nitrate  used  for  20  pounds  of  soil.  Does  this 

suggest  why  soluble  fertiliz- 
ers must  not  be  applied  in 
large  amounts  ? 

100.  Effect  of  deep  plant- 
ing  on   the   germination    of 
seeds.     Place  2  to  3  inches 
of  moist  soil  on  the  bottom  of 
a  glass  jar.     Plant  4  to  5  peas 
near  the  wall   so   that  they 
may  be  observed.    Now  cover 
with  2  inches  more  of  soil  and 
plant  some  more  seed.     Re- 
peat this  .(Fig.  124),  planting 
the  seeds  only  an  inch  deep. 
Keep    the    soil    moist    and 
warm.    Record  what  happens. 

1 01.  Capillary    action     of 
water  on  soil.     Firmly  tie  a 
piece  of  linen  cloth  over  the 

ends  of  several  glass  tubes,  one-half  to  three-fourths  inches 
in  diameter.     Lamp  chimneys  are  suitable.     Fill  one  tube 


FIG.  124. — Effect  of  deep  planting 
on  germination  of  seed. 


PRACTICAL  LABORATORY  EXPERIMENTS      359 

with  sandy  soil,  another  with  clay  soil,  and  a  third  with  a  loam. 
Compact  the  soils  after  each  addition  by  gently  jarring. 
Then  immerse  the  lower  ends  of  the  tubes  in  a  basin  of  water. 
Support  them  upright  and  allow  them  to  stand.  For  one 
week,  measure  each  day  the  height  to  which  the  water  rises. 
What  does  this  show? 

102.  Sedimentation  of  clay.     In  each   of   three   separate 
cylinders,  or  beakers,  place  200  cc.  of  turbid  water  made  by 
shaking  up  some  clay.     To  beaker  No.  1  add  one-half  gram 
of  burned  lime  and  stir;  to  No.  2  add  one  gram  of  burned 
lime  and  stir;  the  third  beaker  is  used  for  purposes  of  com- 
parison, and  no  lime  is  added  to  it.     After  24  hours  observe 
the  beakers,  and  note  the  influence  of  the  lime  in  throwing 
down  the  clay  and  clarifying  the  liquid.     Liming  clay  soils 
makes  them  work  better. 

103.  Effect  of  color  on  soil  temperature.     Fill  two  boxes, 
each  one  foot  square  and  five  inches  deep,  with  soil  and 
gently  compact  this.      Cover  one  with  lampblack  and  the 
other  with  gypsum  or  chalk.     Insert  thermometers  in   the 
soil  to  a  depth  of  1.5  inches  and  expose  the  boxes  equally 
to  the  rays  of  the  sun,  recording  the  reading  of  the  thermom- 
eters every  ten  minutes  for  two  hours.     Arrange  the  results 
in  a  table.     What  is  the  conclusion? 

104.  Effect  of  drainage  on  soil  temperature.       Fill  two 
boxes  as  in  the  above  experiment,  but  have  one  box  lined 
with  tin  or  galvanized   iron  or  oiled  cloth.     Add  water  to 
the  soil  in  the  box  not  lined  until  it  begins  to  drain.     Add  the 
same  amount  to  the  other.     Let  stand  until  the  water  in  the 
unlined  box  has  largely  drained  away.     Take  temperature 
readings  as  in  experiment  103. 


360  CHEMISTRY  AND   DAILY  LIFE 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XV 

105.  Action  of  fertilizers.     Into  each  of  two  boxes,  about 
one  foot  square  and  five  inches  deep,  place  20  pounds  of  or- 
dinary dry  soil.     Before  putting  the  soil   into  one  of  the 
boxes,  add  to  it  the  following  materials,  mixing  them  thor- 
oughly with  the  soil :  5  grams  of  calcium  acid  phosphate, 
3  grams  of  potassium  nitrate,  and  3  grams  of  potassium  sul- 
phate.    Water  the  soils,  and  when  they  have  been  properly 
worked,  plant  in  each  box  25  rape  seeds  and  place  the  boxes 
in  a  greenhouse  or  window.      When  the  plants  are  up,  thin 
them  down  to  16  and  let  them  grow.     Note  the  difference 
in  growth  from  week  to  week.     Try  the  same  experiment, 
using  sand  as  the  soil,  and  note  the  results.     What  elements 
needed  by  the  plants  may  be  lacking  in  the  sand,  and  are  not 
supplied  by  the  fertilizer  you  have  used?     Action  on  acid 
soil:     try  the  same  experiment,    using    an   acid    soil    and 
clover  seed  instead  of  rape  seed.     To  one  of  the  boxes  add 
10  grams  of  finely  ground  limestone.     Why  add  the  lime- 
stone ? 

1 06.  Phosphorus  in  bones.      (1)  To  about  one  gram  of 
bone  ash  in  15  cc.  of  water  add  3  to  5  cc.  of  nitric  acid,  shake 
the  mixture  and  filter.     To  the  warm  filtrate  add  5  to  10 
cc.  of  ammonium  molybdate,  and  warm.     What  is  the  yellow 
precipitate?     What  does  it  indicate?     (2)    In  a  test  tube 
heat  one  gram  of  bone  ash  with  20  cc.  of  distilled  water  and 
filter.     To  the  warm  filtrate  add  5  cc.  of  ammonium  molyb- 
date solution.     Note  the  result,  and  compare  it  with  that 
obtained  in  the  previous  experiment  (1)  in  which  nitric  acid 
was  first  added  to  the  ash.     Try  the  same  experiment  with 
acid  phosphate ;   also  with  floats. 

107.  Solubility  of  potash  fertilizers.      Place   1   gram  of 
kainit  in  a  test  tube,  add  100  cc.  of  water,  and  shake  the  mix- 


PRACTICAL   LABORATORY  EXPERIMENTS       361 

ture.  Does  the  salt  dissolve?  Try  the  same  experiment 
with  saltpeter  (potassium  nitrate) ;  also  with  muriate  of 
potash.  These  salts  are  all  readily  soluble  potash  ferti- 
lizers. 

1 08.  Making  acid  phosphate.     In  a  cigar   box   mix    100 
grams  of  bone  meal  and  100  grams  of  commercial  sulphuric 
acid.     Add  the  acid  slowly,  stirring  constantly  with  an  iron 
rod.     After  all  has  been  added,  allow  the  mixture  to  stand 
for   three   days.      Then   pulverize   and   examine   it.      Test 
1  gram  of  it  for  soluble  phosphates  as  in  experiment  106. 
Also  test  the  solubility  of  floats  in  water. 

109.  Differences  in  volatility  of  ammonium  salts.      In  a 
test  tube  place  2  grams  of   ammonium  carbonate.      Note 
the  odor.     Apply  heat  gently  and  observe  the  result.     The 
ammonium    carbonate    volatilizes    readily    and    may   again 
deposit  on  the  cold  walls  of  the  test  tube.     Try  the  same 
experiment  with  ammonium  sulphate.       This  is  much  less 
volatile.     In  poorly  ventilated  barns,  deposits  of  ammonium 
carbonate  are  frequently  found,  especially  in  horse  stables. 
Gypsum,  i.e.  land  plaster,  when  applied  to  the  manure  con- 
verts some  of  the  ammonium  carbonate  to  ammonium  sul- 
phate and  thus  saves  it. 

no.  Solubility  of  nitrogenous  fertilizers.  Place  10  grams 
each  of  sodium  nitrate,  ammonium  sulphate,  and  dried  blood 
on  filter  papers  in  separate  funnels.  Pour  over  each  sample 
small  portions  of  water,  and  continue  to  leach  the  samples 
with  water  until  100  cc.  of  filtrate  have  been  collected  in 
each  case.  Which  of  these  fertilizers  are  insoluble  in  water? 


362  CHEMISTRY  AND   DAILY  LIFE 

EXPERIMENTS  TO   ACCOMPANY  CHAPTER  XVI 

in.  Losses  from  manure  by  leaching.  Take  one  pound 
of  fresh  manure,  place  it  in  a  large  funnel  having  a  good  wad 
of  cotton  in  the  bottom,  and  leach  the  manure  by  pouring 
on  water  until  one  or  two  liters  of  filtrate  have  been  collected. 
In  a  box  one  foot  square  and  five  inches  deep,  containing 
15  to  20  pounds  of  rather  infertile  soil,  plant  25  rape  seeds. 
In  a  similar  box  containing  the  same  quantity  of  soil,  but  to 
which  the  dung  washings  will  be  added  as  needed,  also  plant 
25  rape  seeds.  After  the  seeds  have  germinated,  thin  down 
to  16  plants.  Keep  both  boxes  properly  watered  in  a  green- 
house or  near  a  window  and  note  the  differences  in  growth. 
This  experiment  gives  an  idea  of  the  great  losses  in  plant 
food  that  may  occur  by  the  leaching  of  manures. 

112.  Loss  of  ammonia  from  manure.     Place  some  fresh 
horse  manure  in  a  glass  bottle  and  stopper  it.     Let  it  stand 
in  a  warm  place  for  24  hours,  then  open  the  bottle  and  note 
the  odor.     The  penetrating  odor  is  due  to  ammonia.     Repeat 
the  above  experiment,  but  over  the  partly  compressed  manure 
place  a  layer  of  moist  dirt  one  inch  thick.     Is  the  odor  of 
ammonia  so  noticeable  ?      Moist  earth  is  a  good  absorbent 
for  ammonia. 

113.  Plant  food  in  urine.     Test  some  urine  (human  or 
animal)  for  potassium  by  the  flame  test  as  in  experiment  56, 
also  for  sodium  as  in  experiment  57.     In  a  test  tube  place 
about  8  cc.  of  urine ;  add  a  few  drops  of  nitric  acid  and  5  cc. 
of  ammonium  molybdate  solution.     Warm  to  65°  C.,  but 
do  not  boil.     A  yellow  coloration  or  precipitate  shows  the 
presence  of  phosphorus.     Why?     There  is  very  little   phos- 
phorus in  the  urine  of  our  domestic  animals.     Most  of  the 
phosphates  leave  the  body  in  the  solid  excreta. 


PRACTICAL  LABORATORY  EXPERIMENTS   363 


EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XVII 

114.  Oxygen  given  off  by  leaves.     Take  a  small  bunch  of 
young,  green,  active  shoots  of  any  plant,  and  place  it  in  the  ap- 
paratus as  shown  in  Fig. 

125.  Set  the  jar  in  the 
brightest  light  available, 
and  repeat  the  experi- 
ment with  another  jar 
kept  in  the  dark.  Ar- 
range a  third  similar  ex- 
periment in  the  light, 
with  water  that  has  been 
boiled  and  then  quickly 
cooled.  As  the  light  falls 
on  the  leaves  in  the  un- 
boiled water,  little  bub- 
bles of  gas  will  begin  to 
appear  at  the  tips  of  the 
leaves.  As  they  accu- 
mulate they  will  ascend 

into  the  test  tube.  No  such  bubbles  will  appear  from  the 
leaves  in  the  dark,  or  from  those  in  the  light  that  are  im- 
mersed in  boiled  water.  Test  the  gas  in  the  test  tube  for 
oxygen  with  a  glowing  splinter.  Explain  the  results  of  these 
three  experiments. 

115.  Carbon  dioxide  taken  up  by  the  leaves.     Arrange  an 
apparatus  as  shown  in  Fig.  126.     Fill  the  glass  tube,  which  is 
from  5  to  6  feet  long,  with  freshly  gathered  leaves  of  grass. 
Use  only  young,  active  leaves.     Set  up  the  tube  horizontally 
in  the  brightest  daylight  available,  and  with  the  aspirator 
slowly  draw  air  first  through  the  tube  and  then  through  the 
wash   bottle   containing   some   barium   hydroxide   solution. 


FIG.  125. —  Oxygen  is  given  off  by  leaves. 


364  CHEMISTRY  AND  DAILY  LIFE 

Barium  hydroxide  is  very  sensitive  to  carbon  dioxide,  be- 
coming milky  with  a  small  quantity  of  the  gas.  If  the  light 
is  good  there  will  be  no  evidence  of  carbon  dioxide  in  the  air 
that  has  been  drawn  over  the  leaves.  Now  detach  the  tube 
of  leaves  and  draw  the  ordinary  air  through  the  tube.  Milk- 


FIG.  126.  —  Green  leaves  take  carbon  dioxide  from  the  air  in  the  sunlight. 

iness  will  soon  appear.     This  experiment  shows  that  green 
leaves  take  carbon  dioxide  from  the  air  in  the  sunlight. 

116.  Germination  of  seeds.  Take  about  20  conveniently 
large  seeds,  such  as  beans  or  corn,  and  soak  them  in  water 
for  a  few  hours.  Then  plant  them  in  moist  sawdust,  cover- 
ing the  seeds  about  half  an  inch  deep.  Keep  them  in  a  warm 
place  for  a  day  or  two  in  order  to  start  germination.  Exam- 
ine the  seeds  from  time  to  time  and  note  their  progress.  How 
long  does  it  take  for  the  seeds  to  grow  a  radicle  an  inch  long  ? 
When  does  the  plumule  appear  ? 


PRACTICAL   LABORATORY  EXPERIMENTS      365 

117.  Influence  of  poisons    and   mutilation   on   germina- 
tion.      Soak  half  a  dozen  beans  for  a  few  hours  and  then 
mutilate  some  of  them  in  various  ways  before  planting  them 
in  moist  sawdust.     Cut  into  the  embryo  of  one  of  the  beans ; 
cut  bits  off  from  the  embryo  of  another;  poison  a  third  by 
touching  it  with  a  trace  of  carbolic  acid ;  treat  another  with 
a  drop  of  boiling  water ;  etc.     Then  set  them  out  in  the  moist 
sawdust  to  germinate.     The  seed  will  not  grow  if  the  embryo 
is  cut  or  killed.     The  healthy  embryo  itself  may  grow  when 
separated  from  the  rest  of  the  seed,  provided  the  embryo 
is  kept  moist  with  a  proper  food  solution  containing  sugars, 
proteins,  and  salts. 

118.  The   germinating    seed    needs  air.     (1)    Put    some 
mustard  seed  into  a  bottle.     Fill  it  completely  with  water. 
Then  stopper  it  and  let  it  stand  in  a  warm  place.     The  seeds 
may  start  to  sprout  because  of  the  dissolved  air  in  the  water, 
but  they  will  soon  stop  growing.     (2)  Grease  the  stopper  of 
a  wide-mouthed  pint  bottle.      Put  into  the  bottle  one-half 
ounce  of  mustard  seed  and  enough  water  to  moisten  the 
seeds  thoroughly.     Stopper  the  bottle  and  set  it  in  a  warm 
place  in  the  dark.     The  seeds  will  germinate,  for  there  is 
some  air  in  the  bottle ;  but  they  will  soon  stop  growing  further 
for  lack  of  air.     Open  the  bottle  and  at  once  insert  a  lighted 
taper.     The  flame  is  extinguished,  indicating  that  the  oxygen 
in  the  bottle  has  been  used  up.     (3)  Decant  some  of  the  air 
from  the  bottle  just  used  into  a  clean  bottle  and  shake  it 
with  clear  limewater.      The  solution  becomes  milky,  indi- 
cating the  presence  of  carbon  dioxide.     Explain  the  results. 

119.  Carbon  in  plants.     Take  some  dry  plant  tissue  from 
growing  plants,  like  beans  or  wheat,  and  place  it  in  a  porce- 
lain dish.     Heat  it  strongly  over  a  Bunsen  flame,  covering 
the  greater  part  of  the  dish  with  a  porcelain  or  iron  cover. 
Thick  gases  will  come  off,  and  these  will  take  fire  if  allowed 


366  CHEMISTRY  AND   DAILY   LIFE 

to  come  into  contact  with  the  flame.  After  a  time,  extin- 
guish the  flame,  by  completely  covering  the  basin.  With- 
draw the  burner,  and  allow  the  dish  and  its  contents  to  cool. 
It  will  be  seen  that  the  interior  of  the  dish  is  covered  with  a 
black  soot  which  is  carbon,  set  free  from  the  plant  tissue. 

1 20.  Nitrogen  in  plants.       The  important  element  nitro- 
gen, which  is  contained  in  the  plant  in  combination  with 
other  elements,  is  lost  during  combustion  and  therefore  is 
not  in  the  ash  of  a  plant.     To  show  its  presence  in  the  plant 
mix  a  gram  or  two  of  dry  plant  material  in  a  test  tube  with 
soda-lime,  and  then  heat  the  whole  directly  in  a  flame;  the 
gases  which  come  off  will  contain  ammonia,  which  can  be 
smelled.     Test  the  gas  also  with  moist  red  litmus  paper. 

121.  Phosphorus  in  seed.     Crush  25  kernels  of  wheat  in 
a  mortar.     Place  the  material  in  an  iron  or  porcelain  cru- 
cible and  heat  it  strongly  over  the  Bunsen  burner.     Do  not 
put  the  cover  on.     When  cool,  transfer  the  charred  mass  to 
a  small  beaker.     Add  10  cc.  of  nitric  acid  and  50  cc.  of  water, 
and  boil  for  10  minutes.     Break  up  the  charred  particles  with 
a  stirring  rod  during  the  boiling.     Filter,  and  to  half  of  the 
warm  filtrate  add  3  cc.  of  ammonium  molybdate  solution.     A 
yellow  precipitate  shows  the  presence  of  phosphorus.     Why  ? 

122.  Calcium  in  clover.     Cut  up  some  clover  hay  with  a 
pair  of  shears.     Place  25  grams  of  it  in  an  iron  crucible  and 
ignite  it  over  the  burner  till  only  ash  is  left.     Transfer  the  ash 
to  a  beaker.     Add  50  cc.  of  water  and  5  cc.  of  nitric  acid  and 
then  heat  and  finally  filter.     To  about  20  cc.  of  the  filtrate 
add  ammonia  water  until  the  solution  just  turns  red  litmus 
blue.     Then  add  5  cc.  of  acetic  acid,  or  more  if  necessary, 
until  the  reaction  is  distinctly  acid  to  litmus.     Now  add  2 
to  4  cc.  of  a  saturated  solution  of  ammonium  oxalate.     A 
white  precipitate  shows  the  presence  of  calcium  in  the  ash. 
The  precipitate  is  calcium  oxalate,  CaC2O4. 


PRACTICAL  LABORATORY  EXPERIMENTS      367 


123.  Potassium  in  plants.     Test  the  ash  from  the  clover 
for  potassium  with  the  flame  test  and  blue  glass  as  described 
in  experiment  56. 

124.  Preparation  of   pectin.     Grate  a   turnip  and   place 
the  material  in  a  linen  bag  and  wash  out  all  the  soluble 
matter.     Place    the    washed 

pulp  in  dilute  hydrochloric 
acid  (1  part  of  concentrated 
acid  to  15  of  water)  and 
let  stand  48  hours.  Then 
squeeze  out  the  acid  liquid. 
Filter  the  liquid  and  to  the 
filtrate  add  an  equal  bulk 
of  alcohol.  The  precipitate 
formed  is  pectin.  The  pres- 
ence of  this  substance  in  fruits 
is  the  cause  of  their  jellying. 

125.  Acids  in  foods.    Vine- 
gar    contains     acetic     acid. 
Taste  some  vinegar,  and  then 
place  25  cc.  of  it  in  a  beaker. 
Add    two    drops  of   phenol- 
phthalein  solution,  and  then 
carefully  add  a  dilute  solution 
of  baking  soda  from  a  bu- 
rette, Fig.   127,   until  a  red 
color    just     appears.      Now 

taste  the  liquid.  It  is  no  longer  acid  in  taste.  The  soda  has 
combined  with  the  acid  to  form  sodium  acetate,  a  salt  which 
has  but  little  taste.  What  gas  escaped?  Baking  soda  is 
often  used  to  neutralize  excessive  acidity  in  cookery,  especially 
when  acid  fruits,  such  as  apples,  plums,  or  lemons,  are  em- 
ployed. 


FIG.  127.  —  Neutralizing  an  acid. 


368  CHEMISTRY  AND   DAILY  LIFE 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XVIII 

126.  Digestion  of   proteins.     Get  a  hog's  stomach  at  a 
slaughterhouse.     Wash  the  stomach  thoroughly  with  water. 
Remove  the  mucous  membrane.     Grind  this  membrane  in 
a  sausage  grinder  and  place  it  in  500  cc.  of  0.2  per  cent  solu- 
tion of  hydrochloric  acid.     Add  10  cc.  of  chloroform  to  pre- 
vent putrefaction.     After  standing  at  ordinary  temperatures 
for  24  hours,  filter  the  solution.     Into  100  cc.  of  this  solution 
place  about  10  grams  of  coagulated  egg  white  made  by  plac- 
ing egg  white  into  boiling  water.     Set  the  dish  and  its  con- 
tents in  a  warm  place,  not  above  100°  F.,  for  24  hours. 
Examine  the  result.     The  protein  has  partly,  if  not  entirely, 
disappeared.     It  has  been  digested  by  the  pepsin  from  the 
stomach. 

127.  Action  of   malt  on  starch.     In  a  mortar   crush  30 
malted  barley  kernels.     Put  this  powder  in  a  small  flask, 
and  add  15  cc.  of  water.     After  24  hours  filter  off  the  solu- 
tion, and  to  the  liquid  add  2  grams  of  flour  and  100  cc.  of 
water.     Se"t  the  flask  away  in  the  cupboard  for  24  hours. 
Then  filter  off  the  solution,  and  test  a  portion  of  the  residue 
for  starch  with  iodine   solution.     Malt    converts    starch  to 
sugars.     Test  some  of  the  solution  for  sugar  with  Fehling's 
solution  as  in  experiment  54.     If  brewer's  malt  cannot  be 
had,  the  barley  grains  themselves  may  be  germinated ;  and 
when  the  sprouts  are  one-half  to  one  inch  long  the  seeds  can 
be  used  in  this  experiment. 

128.  Action  of   saliva  on  starch.     To  obtain   the  saliva 
for  this  experiment,  chew  a  small  piece  of  pure  paraffin,  and 
collect  the  saliva  in  a  beaker.     Make  some  starch  paste  by 
suspending  about  10  grams  of  starch  in  cold  water  and  then 
stirring  in  boiling  water.     Take  25  cc.  of  this  starch  paste  and 
adjust  its  temperature  to  about  104°  F.     Add  5  drops  of 


PRACTICAL  LABORATORY  EXPERIMENTS      369 

saliva  and  stir  thoroughly.  At  intervals  of  a  minute,  remove 
a  drop  of  the  solution  to  a  white  tile  and  test  the  drop  by 
means  of  a  drop  of  iodine  solution.  If  the  blue  color  with 
iodine  still  forms  after  five  minutes,  add  another  5  drops  of 
saliva  and  stir.  The  turbidity  of  the  starch  solution  should 
soon  disappear,  indicating  the  formation  of  soluble  com- 
pounds which  give  no  blue  color  with  iodine.  After  further 
action,  test  the  solution  with  Fehling's  solution.  A  reddish 
brown  precipitate  with  this  reagent  shows  that  the  starch 
has  been  converted  to  the  sugar,  maltose. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XIX 

129.  Water  in  foods.     Mark  two  porcelain  crucibles  with 
your  initials,  using  a  lead  pencil.     Place  them  in  the  flame 
and   heat   them  to  redness   for   five  minutes.     Cool   them 
in  a  desiccator  and  weigh  them.     Into  each  crucible  place 
4  grams  of  flour.     Place  them  in  an  oven  at  95°  to  100°  C. 
and  allow  them  to  remain  for  five  hours.     Cool  them  in  the 
desiccator  for  one-half  hour,  and  weigh  them.     The  loss  in 
weight,  divided  by  the  weight  of  the  sample  (4  grams)  and 
multiplied  by  100  gives  the  per  cent  of  water  in  the  flour. 
Flour  will  contain  from  10  to  15  per  cent  water.     Repeat 
the  experiment  with  grated  turnips,   or  with  butter.     In- 
stead of  porcelain  crucibles  ordinary  tinned  iron  salve  box 
covers  may  also  be  used. 

130.  Starch   and    protein    in    bread.     Make    the   iodine 
(starch)  and  protein  tests  on  samples  of  bread.     Take  some 
of  the  brown  crust  of  the  bread  and  grind  it  up  and  extract 
it  with  water.     Test  this  extract  with  Fehling's  solution. 
If  you  get  a  test  for  sugar,  make  a  similar  test,  using  an  ex- 
tract made  from  a  part  of  the  interior  of  the  same  loaf  of 
bread.     Compare  the  results.     What  are  your  conclusions? 

2s 


370  CHEMISTRY  AND   DAILY  LIFE 

131.  Effect  of  heat  on  potato  starch.     With  the  point  of  a 
knife  scrape  lightly  the  surface  of  a  raw  potato  and  place 
a  drop  of  the  starchy  juice  upon  a  microscope  slide.     Cover 
this  liquid  with  a  cover  glass  and  examine  it  under  the  com- 
pound  microscope.     Draw   the   starch   grains.     Make   this 
examination,  using  a  boiled  potato  and  also  a  baked  potato, 
drawing  the  starch  grains  in  each  case.     Baking  and  cook- 
ing rupture  the  cells  and  thus  it  becomes  easier  to  digest  the 
food  they  contain. 

132.  Starch  grains.     With  a  compound   microscope   ex- 
amine the  starch  grains  of  wheat,  corn,  rice,  and  oats.     Draw 
the  grains  and  compare  these  drawings  with  those  of  the  dif- 
ferent starch  grains  pictured  in  Figs.  86,  87,  and  88.     Pro- 
ceed as  follows :    Place  a  drop  or  two  of  the  starch  water 
made  from  the  grain   on  a  slide.     Cover  the  liquid  with 
a  cover    glass,    and   examine  the   material   under  the  mi- 
croscope. 

133.  Breakfast  foods.     Under   the   microscope,  examine 
two  samples  of  cereal  breakfast  foods.     Compare  what  you 
see  with  the  appearance  of  the  starch  grains  of  wheat,  corn, 
and  oats,  experiment  132.     Tell  from  what  grains  the  break- 
fast foods  were  made. 

134.  Eggs.     Composition  of   eggshell.     Examine   a   por- 
tion of  the  shell  under  the  microscope,  and  note  its  physi- 
cal   character.     Crush  and    grind  an  eggshell.     Extract   it 
thoroughly  with  warm  water,  and  then  dissolve  the  extracted 
mass  in  dilute  hydrochloric  acid.     Observe  that  a  gas  comes 
off.     Hold  in  the  gas  a  drop  of  limewater  on  the  end  of  a 
glass  rod  and  note  how  cloudy  the  liquid  becomes.     Filter 
the  acid  solution,  add  ammonia  water  until  strongly  alka- 
line, and  then  add  5  cc.  of  ammonium  oxalate  solution.     What 
is  the  precipitate  ?     What  is  the  gas  that  was  formed  ?     Why 
must  chickens  be  fed  limestone?    Try  the  same  experiment 


PRACTICAL  LABORATORY  EXPERIMENTS      371 

with  a   piece  of   limestone;   and    also  with  wood    ashes  in 
place  of  eggshell. 

135-  Egg  albumen.  Prick  two  holes  in  an  egg  and  blow 
out  the  white.  Shake  up  a  portion  of  it  with  water  and  note 
that  it  dissolves.  Then  boil  some  of  the  solution.  The 
white  coagulates.  White  of  egg  is  a  protein,  and  serves  to 
nourish  the  growing  chick  during  the  incubation  of  the  egg. 

136.  Yeast.     On  a  watch  glass  mix  thoroughly  a  piece  of 
yeast  of  the  size  of  a  grain  of  wheat  with  about  5  cc.  of  water. 
Then  with  a  stirring  rod  place  a  drop  of  this  solution  on  a 
microscope  slide,  adding  a  drop  of  very  dilute  methyl  violet 
solution.     Cover  with  a  cover  glass,  and  examine  under  the 
microscope.     The  living,  active  cells  appear  colorless,  while 
the  decayed  and  lifeless  ones  are  stained.     Yeast  cells  are 
circular  or  oval  in  shape. 

137.  Carbon  dioxide  from  baking  powder.    Baking  powders 
are  used  for  the  production  of  carbon  dioxide.     Place  20 
grams  of  the  dried  powder  in  a  250-cc.  flask,  provided  with  a 
cork  through  which  passes  a  delivery  tube,  having  its  outer 
end  below  the  surface  of  100  cc.  of   limewater  placed  in  a 
narrow  beaker.     To  preserve    the    limewater    from  contact 
with  the  air,  cover  with  one-fourth  inch  of  kerosene.     When 
water  is  added  to  the  baking  powder,  carbon  dioxide  gas  is 
rapidly  evolved.     The  gas  produces  a  precipitate  in  the  lime- 
water.     What  is  the  precipitate? 

138.  Alum  in  baking  powders.     Burn  two  grams  of  the 
baking  powder  in  a  porcelain  dish.     Extract  the  ash  with 
boiling  water  and  filter.     Add  to  the  filtrate  enough  am- 
monium chloride  solution  so  that  the  mixture  smells  distinctly 
of  ammonia.     The  appearance  of  a  white,  flocculent  pre- 
cipitate, especially  upon  warming,  indicates  the  presence  of 
alum  in  the  powder.     What  is  the  precipitate? 

139.  Testing  baking  powders  for  phosphates.     Dissolve 


372  CHEMISTRY  AND   DAILY  LIFE 

one-half  gram  of  baking  powder  in  5  cc.  of  water  and  add  3"cc. 
of  nitric  water.     Filter,  and  add  3  cc.  of  ammonium  molyb 
date  solution  and  warm  gently.     A  yellow  precipitate  indi- 
cates the  presence  of  phosphates. 

140.  Fat  in  meat.     Grind  up  some  meat  in  a  meat  grinder. 
Place  20  to  30  grams  in  a  flask  and  cover  it  with  50  cc.  of 
gasoline.     Stopper  the  flask  loosely.     Shake  it  occasionally 
and  let  it  stand  one-half  hour.     Pour  the  gasoline  off  into  a 
beaker  and  allow  it  to  evaporate  slowly.     For  this  purpose 
it  may  be  set  outdoors.     Observe  the  fat  left  behind  in  the 
beaker.     Do  the  same  experiment  with  peanuts  instead  of 
meat,  grinding  them  up  well  before  pouring  on  the  gasoline. 
What  are  the  results  ? 

141.  Action  of  iron  compounds  on  tannic  acid.     Make  an 
infusion  of  tea  by  placing  5  grams  of  tea  in  100  cc.  of  boiling 
hot  water  and  stirring  well.     Filter  off  some  of  the  infusion, 
and  add  5  cc.  of  ferrous  sulphate  solution  (made  by  dissolving 
1  gram  of  ferrous  sulphate  in  10  cc.  of  water  and  filtering). 
The  solution  turns  dark  in  color ;  and  if  concentrated  enough 
it  becomes  black.     Try  the  same  experiment  with  an  infusion 
of  hemlock  or  oak  bark.     This  is  the  way  common  ink  is 
made,  only  nutgalls  are  used  instead  of  tea,  or  the  bark  of 
trees.     All  of  these  plant  materials  contain  tannin. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XX 

142.  Microscopic  examination  of  milk.     Place  a  drop  of 
milk  on  a  microscope  slide.     Cover  with  a  cover  glass  and 
examine  the  milk  for  fat  globules  and  for  impurities,  such  as 
hair,  dirt,  etc.     Make  drawings.     Examine  a  drop  of  skimmed 
milk.     How  do  the  two  differ  ? 

143.  Acidity  of  milk.     Test  fresh  milk  with  blue  litmus 
paper.     Let  some  of  the  milk  sour  and  test  this  with  blue 


PRACTICAL  LABORATORY  EXPERIMENTS      373 

litmus  paper.     The  acid  formed  is  lactic  acid,  produced  from 
the  sugar  in  the  milk  by  bacteria. 

144.  Formation  of  lactic  acid.     Place  5   grams  of  milk 
sugar  in  100  cc.  of  water,  add  5  cc.  of  skimmed  milk  and  2  or 
3  crystals  of  sodium  phosphate.     Add  2  or  3  cc.  of  blue  litmus 
solution.     Leave  the  flask  uncorked   in  the   cupboard   for 
24  hours.     Has  the  solution  turned  red?     If  it  has,  lactic 
acid  (the  acid  in  sour  milk)  has  been  formed.     Taste  the 
solution. 

145.  Babcock  test  for  fat  in  milk.     Measure  with   the 
pipette  into  the  test  bottle  17.6  cc.  of  milk.     The  sample 
should  be  carefully  taken  and  well  mixed.     Add  17.5  cc.  of 
commercial  sulphuric  acid  (sp.  gr.  1.83)  from  the  cylinder; 
mix  the  acid  and  milk  by  rotating  the  bottle.     Then  place 
the  test  bottle  in  the  centrifugal  machine  and  whirl  5  minutes 
at  a  rate  of  800  to  1200  revolutions  per  minute.     Add  suffi- 
cient hot  water  to  the  test  bottle  to  bring  the  contents  up  to 
the  shoulder,  and  whirl  two  minutes.     Then  fill  the  bottle 
with  water  to  near  the  top  of  the  graduations  and  whirl  again 
for  two  minutes,  and  then  read  the  fat.     Read  from  the  ex- 
treme lowest  to  the  highest  point.     Each  large  division,  as 
from  one  to  two,  represents  a  whole  per  cent.     Each  small 
division  represents  0.2  of  a  per  cent.     Test  a  Holstein  milk 
and  a  Jersey  milk.     Test  the  milk  from  the  cows  on  your 
farm. 

146.  Formalin  in  milk.     The  instructor  should  place  some 
of  the  preservative  in  milk  and  have  the  pupils  detect  it. 
To  10  cc.  of  milk  add  10  cc.  of  a  solution  of  concentrated  hy- 
drochloric acid  containing  per  liter  2  cc.  of  10  per  cent  ferric 
chloride  solution.     Pour  the  mixture  in  a  teacup  and  heat  it 
slowly  to  boiling  over  a  flame,  giving  the  cup  a  slight  rotary 
motion.     If  formalin  is  present,  a  violet  coloration  will  appear. 

147.  Test  for  oleomargarine.     Foam  test  for  purity  of 


374  CHEMISTRY  AND  DAILY  LIFE 

butter.  Heat  about  3  grams  of  the  sample  in  a  large  iron 
spoon  over  a  low  flame,  stirring  constantly  with  a  splinter. 
Genuine  butter  will  boil  quietly,  with  the  production  of  con- 
siderable froth  or  foam.  Oleomargarine  and  renovated 
butter  will  sputter  and  make  much  more  noise.  Always 
compare  by  making  a  simultaneous  test  with  genuine  butter. 

148.  Waterhouse  test.     Into  a  small  beaker  pour  50  cc. 
of  sweet  milk,  heat  nearly  to  boiling,  and  add  5  to  10  grams  of 
butter  or  oleomargarine.     Stir  with  a  glass  rod  until  the  fat 
is  melted.     Then  place  the  beaker  in  cold  water  and  stir  the 
milk  until  the  temperature  falls  sufficiently  for  the  fat  to 
congeal.     At  this  point  the  fat,  if  the  sample  is  oleomargarine, 
can  be  collected  into  one  lump  by  means  of  a  rod.     If  it  is 
butter,  it  will  granulate  and  cannot  be  thus  collected. 

EXPERIMENTS  TO  ACCOMPANY  CHAPTER  XXI 

149.  Purity  of   Paris   green.     Take  about  one  gram  of 
Paris  green.     Put  it  in  a  beaker  and  add  25  cc.  of  ammonia 
water.     Stir  and  let  it  stand  for  five  minutes.     If  the  "  green  " 
is  pure,  it  will  form  a  clear,  dark  blue  solution,  and  leave  no 
solid  residue. 

150.  Preparation  of  lime-sulphur.     Slake  25  grams  of  lime 
in  200  cc.  of  water.     Add  50  grams  of  flowers  of  sulphur. 
Shake  the  mixture  vigorously,  and  heat  it  in  a  steam  bath 
with  frequent  shaking.     Finally  place  it  over  a  wire  gauze 
or  a  free  flame  and  boil  for  half  an  hour.     The  mixture  must 
be  watched  and  occasionally  stirred  in  order  to  avoid  violent 
bumping.     After  boiling,  allow  all  to  stand  and  settle.     Note 
the  color  of  the  liquid  and  the  character  of  the  sediment. 

151.  Preparation   of    Bordeaux    mixture.     Dissolve    0.5 
pound  of  copper  sulphate  in  2  pounds  of  hot  water.     Also 
slake  0.3  to  0.4  pound  of  lime  in  2  pounds  of  water  and  strain 


PRACTICAL  LABORATORY   EXPERIMENTS      375 

the  liquid  through  a  cheesecloth  into  a  pail  so  as  to  remove 
the  coarse  material.  The  solution  of  copper  sulphate  is  then 
poured  into  the  pail  and  all  is  well  stirred.  In  the  preparation 
of  Bordeaux  mixture  it  is  the  aim  to  use  just  enough  lime  to 
combine  with  all  of  the  copper  sulphate.  Test  the  mixture 
with  litmus  paper.  If  it  is  acid,  enough  more  lime  should 
be  added  to  turn  the  litmus  blue,  The  ferrocyanide  test 
can  also  be  performed  as  follows :  Filter  some  of  the  finished 
mixture,  and  add  a  few  drops  of  potassium  ferrocyanide. 
If  a  reddish  brown  precipitate  or  color  appears,  more  lime 
should  be  added.  What  is  the  reddish  brown  precipitate  ? 

152.  Destruction  of  germinating  power  by  formalin. 
Place  about  6  or  8  kernels  of  different  grains,  such  as  corn, 
barley,  and  wheat,  in  a  solution  of  formalin  of  20  per  cent 
strength.  Leave  them  there  for  half  an  hour.  Remove 
the  seeds,  wash  with  water,  and  place  them  in  moist  sawdust 
for  germination.  Do  they  germinate?  What  care  must  be 
practiced  in  treating  seeds  with  such  poisons? 


LISTS  OF  APPARATUS  AND  CHEMICALS  NECESSARY 
FOR  THE  EXPERIMENTS  DESCRIBED  IN  THIS 
CHAPTER 

GENERAL  LABORATORY  APPARATUS 

1  Babcock  tester. 

1  Microscope. 

1  Inexpensive  balance  sensitive  to  1  eg.,  and  set  of  weights,  50  gr. 

to  1  eg. 
1  Drying  oven  (copper). 

1  Water  bath  (6  holes). 

2  Mortars  (4  in.),  preferably  of  porcelain,  though  glass  mortars  will 

do. 

2  Thermometers  (0°-120°). 
4  Burettes,  50  cc.,  and  holders. 
2  Condensers  (Liebig). 


376  CHEMISTRY  AND   DAILY   LIFE 

1  Gross  corks,  sizes  7,  8,  9,  10,  and  12. 

1  Cork  borer,  set  of  six. 

2  500-cc.  cylinders. 

6  Cobalt  glasses  10  cm.  square. 
1  Magnet  (horseshoe). 

4  Pneumatic  troughs,  galvanized  iron,  1  ft.  long,  8  in.  high,  and  8 
in.  wide,  or  can  use  1-gal.  stoneware  milk  pans. 

3  Platinum  wires,  4  in.  long,  about  No.  26  B.  &  S.  guage. 
1  Blast  lamp,  bellows  and  rubber  tubes. 

10  Ib.  Glass  tubing,  sizes  up  to  f  in.  int.  diam. 

4  Retorts  (glass)  500  cc. 

1  Dozen  cylinders  100  cc. 

Tacks,  nails,  brads,  carpenters'  tools,  etc.,  which  can  always  be 
obtained  from  local  dealers,  have  not  been  mentioned  here.  With 
the  aid  of  carpenters'  and  tinners'  tools  many  useful  pieces  of  ap- 
paratus can  be  constructed  by  the  students.  Often  the  local  tinner 
will  make  a  piece  of  apparatus  that  will  serve  as  well  as  one  secured 
elsewhere  at  higher  cost. 

LIST  OF  APPARATUS  USED  BY  EACH  STUDENT 

1  Bunsen  burner  and  tubing,  or  alcohol  lamp. 

2  Stirring  rods. 

4  Watch  glasses  (diam.  3  in.). 
2  Erlenmeyer  flasks  (300  cc.). 
25  Filter  papers  (11  cm.). 
1  Box  matches. 

1  Wire  gauze  (4  in.  square). 

2  Crucibles  (porcelain,  diam.  3.5  cm.) 

1  Test  tube  brush. 

2  Funnels  (diam.  6.5  cm.). 
1  Sand  bath  (4  in.  diam.). 

1  Test  tube  stand. 
1  Wooden  stand  for  funnels. 
12  Test  tubes  12  cm.  long,  diam.  about  1.7  cm. 
6  Beakers  (nest  100  to  600  cc.). 

1  Casserole  (200  cc.). 

2  Evaporating  dishes  (diam.  7.5  cm.). 
1  Crucible  tongs  (9  inches). 


PRACTICAL  LABORATORY   EXPERIMENTS       377 

1  Test  tube  clamp. 

1  Water  bath  (copper). 

2  Aluminum  dishes  (2£  in.  diam.). 

2  Feet  of  glass  tubing  (soft),  ext.  diam.  6  mm. 

1  File  (15  cm.  long),  triangular. 

1  100-cc.  cylinder. 

1  Bottle  each  of  blue  and  red  litmus  paper. 

1  Ring  stand  and  rings. 

1  Deflagrating  spoon. 

4  Bottles  (wide  mouth)  250  cc. 
Rubber  tubing  2  ft.  (int.  diam.  5  mm.). 

2  Flasks  500  cc. 
1  Thistle  tube. 

1  Desiccator. 

1  Iron  crucible  50  cc. 


CHEMICALS  FOR  TEN  STUDENTS 

GRAMS 

Acid,  Hydrochloric,  sp.  gr.  1.2         .        .        .        .  1500 

Nitric,              sp.  gr.  1.4         .        .        .        .  1000 

Sulphuric,        sp.  gr.  1.84        .        .        .        .  2000 

Acetic  (50%) 200 

Alcohol 100 

Alum  (potassium) .  25 

Aluminum  chloride 25 

Ammonium  carbonate 50 

Ammonium  chloride 250 

Ammonium  hydroxide,  sp.  gr.  0.9   .         .         .         ,  1500 

Ammonium  oxalate 25 

Ammonium  nitrate 100 

Ammonium  sulphate       .        .        .        .        .        .100 

Ammonium  molybdate 50 

Arsenic  trioxide 100 

Barium  chloride 20 

Barium  hydrate 20 

Bone  black 100 

Bone  ash          .         .         : 100 

Borax 50 

Calcium  chloride  (granular)     .        .        .        .        .  200 


378  CHEMISTRY  AND   DAILY  LIFE 

GRAMS 

Calcium  sulphate  (gypsum)     .         .         .         .         .  50 

Calcium  carbonate  (marble) 50 

Carbon  bisulphide 30 

Citric  acid       .                 25 

Charcoal,  ten  pieces  8  cm.  X  4  cm. 

Cochineal 5 

Cobalt  nitrate 10 

Copper  (turnings  or  scrap)       .         .         .                 .  250 

Copper  oxide  (black) 50 

Copper  sulphate 100 

Formalin 50 

Fuchsine          ......;.  25 

Glucose  (sirup) 1000 

Iron  chloride   .         .         .         .                 .         .         .  30 

Iron  powder 25 

Iron  sulphate  (ferrous) 75 

Iron  sulphide 250 

Iodine 10 

Indigo 15 

Lime 50 

Logwood 10 

Lead  acetate    . 25 

Lead  (cuttings  from  lead  pipe)        .        .        .        .100 

Lead  nitrate 10 

Litmus 10 

Magnesium  carbonate 50 

Magnesium  sulphate 20 

Magnesium  wire  or  ribbon 10 

Manganese  dioxide 1000 

Methyl  violet          .......  5 

Mercury 100 

Mercuric  chloride 20 

Paraffin 10 

Phenolphthalein 5 

Phosphorus,  yellow 10 

Potassium  carbonate 50 

Potassium  chlorate 250 

Potassium  sulphate 20 

Potassium  dichromate  25 


PRACTICAL   LABORATORY  EXPERIMENTS       379 

GRAMS 

Potassium  hydroxide 50 

Potassium  iodide •  .  50 

Potassium  nitrate    .                  25 

Potassium  permanganate 10 

Potassium  ferrocyanide 25 

Rochelle  salts 20 

Silver  nitrate    . 10 

Sodium  (metallic) 5 

Sodium  bicarbonate 20 

Sodium  carbonate 100 

Soda-lime         .  ....  .100 

Sodium  hydrogen  phosphate    .    •     .         .         .         .  20 

Sodium  hydroxide    .......  400 

Sodium  nitrate 200 

Sodium  silicate  (water  glass)    .         .         .         .         .  100 

Sodium  sulphate 10 

Strontium  chloride 10 

Sulphur 200 

Tannic  acid     .         .        .        .        .        .        .        .  20 

Tin 30 

Zinc  (granulated)     .         .         .         .         .         .         .  1000 

Zinc  sulphate  (crystals) 100 

This  list  does  not  include  common  materials  that  are  always 
easily  obtained,  as  sugar,  salt,  lard,  tallow,  clay,  starch,  cotton,  iron, 
wire,  gasoline,  benzine,  chloroform,  bleaching  powder  (chloride  of 
lime),  tartar  emetic,  turpentine,  etc. 

For  the  convenience  of  teachers  the  names  of  a  number  of  firms 
from  whom  apparatus  and  chemicals  may  be  purchased  are  here 
given:  E.  H.  Sargent  &  Co.,  Chicago,  111.;  Eimer  and  Amend, 
New  York  City ;  Bausch  and  Lomb,  Rochester,  N.  Y. ;  Arthur  H. 
Thomas  Co.,  Philadelphia,  Pa. ;  Scientific  Materials  Co.,  Pittsburg, 
Pa. ;  Henry  Heil  &  Co.,  St.  Louis,  Mo. ;  Denver  Fire  Clay  Co., 
Denver,  Col. ;  Kny-Scheerer  Co.,  New  York  City. 


INDEX 


Acetic  aldehyde,  99. 
Acetylene,  93. 
Acid,  acetic,  41,  98. 

benzoic,  104. 

boric,  42,  74. 

butyric,  105. 

carbolic,  103. 

carbonic,  89. 

citric,  105. 

definition  of,  48. 

formic,  98. 

hippuric,  105. 

hydriodic,  57. 

hydrobromic,  56. 

hydrochloric,  53,  336. 

hydrofluoric,  52. 

lactic,  41,  104. 

malic,  41,  104. 

muriatic,  53. 

oxalic,  41,  104. 

phosphate,  208,  220,  361. 

phosphoric,  70. 

Prussic,  123. 

pyrogallic,  104. 

salicylic,  101. 

silicic,  42,  78. 

sulphuric,  61. 

sulphurous,  63. 

tartaric,  41,  104. 

valeric,  105. 
Acids,  41. 

in  fruits,  335. 

in  plants,  252. 

in  silage,  335. 
Acidulated  rock,  220. 
Air,  carbon  dioxide  in,  30. 

composition  of,  30. 

in  the  lungs,  262. 

moisture  in,  31. 

nitric  acid  in,  35. 
Ajax,  276. 


Alabaster,  130. 
Albumen,  253. 

in  milk,  294. 
Albuminoids,  114. 
Albumins,  114. 
Alcohol,  absolute,  112. 

amyl,  102. 

denatured,  101. 

grain,  98. 

wood,  98. 
Alfalfa,  287. 
Alkalies,  42. 

metals  of,  118. 

Alkaline  earths,  test  for,  347. 
Alkaloids,  115. 

Allotropic  form  of  phosphorus, 
Allspice,  283. 
Alum,  274. 

ammonium,  143. 

baking  powders,  144. 

potassium,  143. 

sodium,  143. 

testing  for,  349. 
Alumina,  141. 
Aluminum,  140. 

bronze,  142. 

metal,  142. 

paint,  142. 

sulphate,  143. 
Amalgams,  153. 
Amides,  253. 
Ammonia,  aqua,  38. 

composition  of,  37. 

from  coal,  37. 

from  manure,  362. 

preparation  of,  334. 

properties  of,  38. 

water,  38. 
Ammonium  bicarbonate,  126. 

chloride,  39. 

molybdate,  157. 

salts  in  soil,  39,  361. 

sulphate,  39,  216. 


381 


382 


INDEX 


Amyl  acetate,  101. 

alcohol,  102. 
Amylopsin,  262. 
Analysis,  48. 
Aniline,  104. 

dyes,  104. 
Animal  foods,  284. 

heat,  258. 
Animals,  255. 

action  in  soil,  196. 

carbohydrate  in,  257. 

fat  in,  257. 

mineral  matter  in,  255,  256. 

protein  in,  256. 

water  in,  255. 

work  by,  257. 
Anthracite,  84. 
Antidote,  for  arsenic,  71. 
Antimony,  71. 
Antiseptic,  defined,  20. 
Ants,  as  soil  formers,  197. 
Apparatus,  list  of,  375,  376. 
Apparatus  dealers,  379. 
Aqua  regia,  147. 
Aristotle,  2. 
Armor  plate,  160. 
Arsenic,  71. 

antidote  for,  71. 

white,  309. 
Arsenious  oxide,  71. 
Asbestos,  79,  136. 
Ash  in  plants,  12,  329. 
Asphalt,  177. 

solubility  of,  354. 
Atropa  belladonna,  115. 
Atropine,  115. 

B 

Babbitt  metal,  71,  155. 
Babcock,  portrait,  305. 
Babcock  test,  303,  373. 
Bacon,  smoking,  104. 
Bacteria  in  food,  273. 

in  fruit,  279,  280. 
Bagasse,  111. 
Baking,  271. 
Baking  powder,  274. 

alum,  144,  275,  371. 

carbon  dioxide  in,  371. 

phosphate,  275,  371. 

tartrate,  275. 
Baking  soda,  127,  274. 


Balanced  ration,  265. 
Banana  oil,  101. 
Barium  nitrate,  129. 

sulphate,  129,  347. 
Barley,  270. 
Barytes,  129. 
Base,  definition  of,  49. 
Basic  lead  acetate,  156. 
Basic  slag,  218,  221. 
Bate  liquor,  185. 
Batteries,  blue  cup,  158. 

primary,  158. 
Battery  carbons,  158. 
Baume  hydrometer,  312. 
Bauxite,  140. 
Beers,  101. 
Beet,  leaves  for  silage,  288. 

roots,  278. 

sugar,  109,  249. 
Bell  metal,  152. 
Bengal  lights,  129. 
Benzene,  103. 
Benzine,  91. 
Bessemer  process,  165. 
Bioses,  108. 
Bismuth,  72. 

subnitrate,  72. 
Blackjack,  64,  157. 
Black  varnish,  177. 
Blast  furnace,  161,  162. 
Blaugas,  93. 

Bleaching  powder,  55,  317,  33' 
Bleeding,  stoppage  of,  167. 
Blood  charcoal,  81. 
Blood  poisoning,  74. 
Blood  stains,  356. 
Blue  glass,  161. 
Blue  print,  paper,  167. 

making  of,  352. 
Bluing,  354. 
Bone,  ground,  218. 

steamed,  219. 
Bone  black,  81. 
Bones,  218. 

phosphorus  in,  360. 
Boracic  acid,  74. 
Borax,  128. 

occurrence  of,  74. 

uses  of,  75. 
Bordeaux,  acid  test  for,  316. 

mixture,  152,  314. 

preparation  of,  374. 
Boric  acid,  74,  340. 


INDEX 


383 


Boron,  74. 
Bottom  lands,  195. 
Boussingault,  portrait,  201. 
Bowlders,  193. 
Bran,  271. 
Brass,  152,  159. 

copper  in,  350. 
Bread,  270. 

making,  274. 

protein  in,  369. 

starch  in,  369. 
Breakfast  foods,  276,  370. 
Brewer's  grains,  276. 
Brewing,  276. 
Bricks,  145. 
Brimstone,  59. 
Britannia  metal,  154. 
Bromine,  preparation  of,  55. 

properties  of,  56. 

vapors,  337. 
Bronzes,  152. 
Brucine,  115. 
Buckskin,  185. 
Bullets,  72. 
Bunsen  burner,  85. 
Butter,  299. 

composition  of,  300. 

fertility  in,  230. 

sweet  cream,  299. 


Cabbage,  278. 

Cadaverine,  114. 

Calcined  soda,  126. 

Calcium,  acid  phosphate,  274. 

carbide,  93. 

carbonate,  130. 

chloride,  130. 

nitrate,  132. 

phosphate,  66,  132. 

silicate,  133. 
Calomel,  153. 
Camembert  cheese,  302. 
Cane  sugar,  108,  249. 

inversion  of,  109. 
Cunning  of  fruit,  279. 
Caoutchouc,  187. 
Capillarity,  209. 
Capillary  water,  210,  358. 
Caramel,  110,  272. 
Carbohydrate,  105,  247. 

digestion  of,  262. 


Carboleum,  318. 
Carbolic  acid,  103,  318. 
Carbon,  81. 

absorbing  power  of,  341. 

bisulphide,  64,  314. 

cycle,  88. 

dioxide,  preparation  of,  341. 

dioxide  in  air,  30,  333. 

monoxide,  86. 

preparation  of,  341. 

reducing  power  of,  341. 

tetrachloride,  95. 
Carbonated  waters,  88. 
Carbonate  of  potassium,  120. 
Carbonates,  89. 
Carboneum,  95. 
Carnallite,  119. 
Carrots,  278. 
Casein,  294,  304. 
Cassiterite,  153. 
Cast  iron,  163. 
Caustic  soda,  125. 
Cells,  238. 
Celluloid,  107. 
Cellulose,  105,  250. 

nitrates  of,  106. 
Cement,  for  floors,  131. 

natural,  134. 

Portland,  133. 
Centrifuge,  111. 
Cereals,  270. 

composition  of,  270. 
Cerium,  146. 
Chalk,  130. 
Chamois  skin,  185. 
Charcoal,  81. 
Cheese,  300. 

composition  of,  302. 
Chemical  change,  4,  326,  327. 
Chemical  equations,  45. 
Chemicals,  list  of,  377. 
Chili  saltpeter,  36,  121,  217. 
Chloride  of  lime,  55,  317. 
Chlorine,  53. 
Chlorine  water,  55. 
Chloroform,  95. 
Chlorophyl,  168,  245. 
Chrome  green,  156,  174. 

steel,  156. 

tanning,  185. 

yellow,  156,  174. 
Chromium,  156. 
Churning,  299. 


384 


INDEX 


Cider,  hard,  284. 
Cinchonine,  115.  • 

Cinnabar,  153,  174. 
Cinnamon,  283. 
Cisterns,  16. 
Clay,  79,  144,  192,  198. 

puddling  of,  357. 

settling  of,  359. 
Cloth,  dyeing  of,  354. 
Clouds,  10. 
Clover,  287. 

calcium  in,  366. 
Coal,  83. 
Coal  gas,  84. 
Coal  tar  dyes,  104. 
Cobalt,  160. 

bead,  351. 
Cocaine,  115. 
Cocoa,  282. 
Codeine,  115. 

Coefficient  of  digestibility,  263. 
Coffee,  282. 

stains,  356. 
Coins,  silver,  48. 
Coke,  81. 
Colemanite,  75. 
Collodion,  36,  106. 
Collostrum,  295. 
Common  salt  as  fertilizer,  223. 
Compound,  denned,  6. 
Compounds,  326. 
Concrete,  134. 

reenforced,  134. 
Condensed  milk,  302. 
Contact  poisons,  308,  311. 
Cooking,  271. 

effect  of,  272. 
Copal,  176. 
Copper,  150. 

acetate,  100. 

alloys  of,  148,  150. 

cleaning  of,  152. 

in  coin,  349. 

plating,  152. 

properties  of,  349. 
Copperas,  166. 
Corks,  fitting  of,  322. 
Corn,  270. 

Corn,  popping  of,  273. 
"Corn  flakes,"  277. 
Corn  starch,  275. 
Corn  stover,  288. 
Correcting  soil  acidity,  357. 


Corrosive  sublimate,  153,  316. 
Cottage  cheese,  301. 
Cotton,  180. 

burning  of,  353. 
Cotton  seed  meal,  217. 
Cotton  seed  oil,  102. 
Cream,  297. 

Cream  of  tartar,  104,  274. 
Cream  separators,  298. 
Creosol,  104,  318. 
Creosote,  98,  104,  318. 
Crude  fiber,  247. 
Cryolite,  141. 
Cyanides,  313,  314. 


Davy,  portrait,  124. 

Definite  proportions,  law  of,  44. 

Denatured  alcohol,  101. 

Depilation,  183. 

Developer  in  photography,  149. 

Dew,  10,  32. 

Dextrine,  107,  249. 

Dextrose,  108. 

Dialysis,  78. 

Diamond,  82. 

Diastase,  112,  276. 

Digestibility  of  feeds,  263. 

Digestion,  258. 

of  proteins,  368. 
Dioxygen,  28. 
Distillation,  destructive,  38. 

dry,  38. 

Distilled  water,  10,  328. 
Distiller's  grains,  276. 
Dolomite,  89,  136. 
Double  decomposition,  48. 
Drainage,  210. 
Dried  blood,  217. 
Dried  fruit,  281. 
Driers,  172. 
Dry  batteries,  158. 
Dry  farming,  209. 
Dutch  metal,  152. 
Dyestuffs,  104,  182. 
Dynamite,  36,  80,  106. 
Dysentery,  remedy  for,  72. 


E 


Earthenware,  145. 
Earthworms,  action  of,  196. 


INDEX 


385 


Ebonite,  189. 
Egg  albumen,  371. 
Eggs,  286. 

composition  of,  370. 
Elastin,  114. 
Elements,  ancient  idea  of,  2. 

chemical,  list  of,  3. 

classification  of,  6. 

defined,  2. 

essential,  in  plants,  119. 
Emery,  140. 
Enzymes,  259. 
Epsom  salts,  66,  137. 
Equivalents,  hydrogen,  45. 
Esters,  101. 
Etching  glass,  52. 
Ether,  103. 
Ether  extract,  251. 


Face  powder,  137. 
Fat,  digestion  of,  262. 

in  meat,  372. 
Fats,  250,  251,  345. 
Fattening  animals,  266. 
Feeding  standards,  263. 
Fehling's  solution,  108,  346. 
Feldspars,  79,  119. 
Fermentation,  alcoholic,  342. 
Ferments,  unorganized,  114. 
Ferric  chloride,  116,  167. 

oxide,  116. 
Ferrous  chloride,  116. 

oxide,  116. 

sulphate,  116. 
Fertility,  factors  of,  202. 
Fertilizer,  phosphatic,  218. 
Fertilizers,  action  of,  360. 

analysis  of,  226,  227. 

commercial,  214. 

elementary  system,  227. 

experimenting  on,  224. 

home  mixing  of,  224. 

indirect,  222. 

laws  on,  226. 

mixed,  223. 

nitrogenous,  216. 

selection  of,  224. 

special,  224. 
Filtering,  323,  324. 
Fire  bricks,  146. 
Fire  clay,  146. 

2c 


Fires,  extinguishing,  96. 
Fish,  as  fertilizer,  217. 

as  food,  286. 

smoking,  104. 
Fixation  of  nitrogen,  207. 
Flashlight  powder,  136. 
Flaxseed,  172. 
Floats,  207,  219. 
Flour,  107,  271. 
Fluorine,  52. 
Fly  removers,  318. 
Fogs,  10. 
Foods,  acids  in,  367. 

animal,  269. 

human,  269. 

water  in,  369. 
Foodstuffs,  classes  of,  246. 
Fool's  gold,  64. 
Forage,  287. 
"  Force,"  276. 
Formaldehyde,  98. 
Formalin,  98,  316. 

action  on  seeds,  375. 

in  milk,  373. 

preparation  of,  351. 
Formates,  98. 
Fractional  distillation,  91. 
Fructose,  108,  250. 
Fruit  stains,  355. 
Fruit  sugar,  108. 
Fruits,  278. 

Fundamental  considerations,  1. 
Fungicides,  314. 
Furs,  186. 


Galenite,  64,  154. 

Galvanized  iron,  157. 

Gasoline,  91. 

Gelatin,  286. 

German  silver,  152,  160. 

Germination,  239,  240,  364. 

Germol,  318. 

Germs  in  water,  17. 

Gin,  112. 

Glaciers,  193. 

Glass,  134,  135. 

quartz,  77. 
Glass  tubing,  bending  of,  322. 

cutting  of,  321. 
Glauber's  salt,  128. 
Glazes,  145. 


386 


INDEX 


Globulin,  253. 
Glucose,  108,  249. 
Glue,  286. 
Gluten,  107. 
Gluten  feed,  276. 
Glycerine,  92,  101. 
oleate,  102. 
palmitate,  102. 
stearate,  102. 
Glycogen,  257. 
Gold,  147. 

copper  alloys  of,  48. 
Granitic  rocks,  79. 
"Grape-nuts,"  276. 
Grape  sugar,  108,  249. 
Graphite,  82. 
Grass  stains,  256. 
Gravitational  water,  210. 
Grease  spots,  251,  343. 
Green  manuring,  236. 
Green  vitriol,  166. 
Growing  animals,  266. 
Guajacol,  104. 
Guano,  218,  219. 
Guncotton,  36,  106. 
Gun  metal,  152. 
Gunpowder,  black,  121. 

smokeless,  106. 
Gutta-percha,  189. 
Gypsum,  64,  130. 
as  fertilizer,  216. 

H 

Hail,  32. 

Hair,  as  fertilizer,  217. 

Halogens,  52. 

Ham,  smoking,  104. 

Hammer  black,  166. 

Hard  soap,  preparation,  342. 

Hay,  287. 

Heat  as  disinfectant,  319. 

Heavy  spar,  219. 

Hellebore,  310. 

Hematite,  161. 

Hemoglobin,  168. 

Hippuric  acid,  206. 

Hoof  meal,  217. 

Hornblende,  79,  136. 

Horn  meal,  217. 

Human  foods,  269. 

Humus,  199,  212. 

Hunyad  spring,  137. 


Hydrocarbons,  91. 
Hydrochinone,  104. 
Hydrogen,  dioxide,  28. 

equivalent,  45. 

occurrence,  22. 

peroxide,  28. 

preparation  of,  330. 

properties  of,  22. 

sulphide,  63,  339. 
Hydrocyanic  acid  gas,  313. 
Hydroscopic  water,  210. 
Hypo,  128. 
Hyposulphite  of  soda,  128. 


Ice  cream,  302. 
Indian  corn,  275. 
Infusorial  earth,  80. 
Ink,  167,  352. 
Ink  stains,  355. 
Insecticides,  gaseous,  313. 
Insect  powder,  311. 
Invertase,  110. 
Iodine,  56. 

action  on  starch,  57. 

vapors,  337. 
[odoform,  95. 
Iron,  change  to  ferric,  352. 

compounds  with  tannic  acid,  372. 

metal,  161. 

pyrites,  64. 

rust,  removal  of,  354. 

rusting  of,  166. 

sulphate,  352. 
ridium,  147. 
singlass,  286. 
soprene,  187. 


apan  driers,  173. 
elly  making,  250. 
unket  tablets,  294. 

K 

finite,  119,  222. 
Calsomine,  177. 
taolin,  79,  144. 
Ceratin,  114. 
Cerosene,  91. 

emulsion,  312. 
Cohlrabi,  278, 


INDEX 


387 


Lactic  acid,  373. 
Lactometer,  340. 
Lactose,  108,  113. 
Lampblack,  81. 
Land  plaster,  131,  223. 
Lard,  hogs',  120. 
Latex,  186. 
Lead,  154. 

acetate,  100. 

action  of  water  on,  351. 

alloys  of,  154. 

arsenate,  71,  156,  310. 

chr6mate,  351. 

colic,  156. 

salts  of,  350. 

storage  battery,  155. 

sugar  of,  156. 
Leaf,  action  of,  242,  246. 
Leather,  bating,  185. 

box  calf,  186. 

gelatin  in,  354. 

kid,  185. 

making  of,  183. 

Morocco,  184. 

Russia,  185. 

soft,  184. 

sole,  185. 

split,  185. 

tawing  process,  185. 

waste,  217. 
Leaves,  carbon  dioxide  from,  363. 

evaporation  from,  245. 

oxygen  from,  363. 
LeBlanc  soda  process,  125. 
Lecithin,  67. 
Legumes,  use  of,  236. 
Levulose,  108,  109. 
Lice  exterminator,  318. 
Liebig,  portrait,  frontispiece. 
Lime,  130. 

air  slaked,  223. 

as  disinfectant,  317. 

deposits  of,  329. 

quality  of,  348. 

value  of,  222. 
Limestone,  89,  130. 

as  fertilizer,  216. 

ground,  223. 

weathering  of,  357. 
Lime  sulphur,  311,  374. 
Limonite,  161. 


Linen,  182. 

Linseed  oil,  171,  172,  353. 

Lipase,  262. 

Liquids,  heating  of,  325. 

pouring  of,  323. 
Litharge,  155. 
Lithium,  118,  123. 
Lithophone,  175. 
Loam,  198. 
Loess,  195. 
London  purple,  310. 
Lubricating  oils,  91. 
Lunar  caustic,  148. 
Lysol,  318. 

M 

Magnalium,  142. 
Magnesium,  136. 

burning  of,  348. 

carbonate,  137. 

chloride,  137. 

oxide,  137. 
Magnetite,  161. 
Malleable  iron,  164. 
Maltose,  108,  112,  250. 
Manganese,  bronze,  159. 

dioxide,  159. 

metal,  159. 

salts,  160. 
Manure,  ammonia  in,  233. 

cold,  229. 

composition  of,  230. 

effect  in  field,  234,  235. 

fermentation  of,  233. 

hot,  230. 

increasing  value  of,  231. 

kinds  of,  229. 

leaching  of,  362. 

liquid,  232. 

losses  of,  232,  233. 

reenforcing  of,  231. 

saving  of,  233,  234. 

spreader,  235. 

storing  of,  234. 

value  of,  229. 
Marble,  89,  130. 
Marsh  gas,  93. 
Mastication,  259. 
Matches,  69. 

safety,  69. 

Swedish,  69. 
Meal,  271. 


388 


INDEX 


Meat,  284. 
Meat  scraps,  217. 
Medium  ratio,  264. 
Meerschaum,  79,  136. 
Mercuric  chloride,  316. 
Mercury,  152. 

antidote  for,  350. 

fulminating,  106. 

preparation  of,  350. 
Metalloids,  6. 
Metals,  6. 

base  forming,  49. 
Methane,  93. 
Methyl  alcohol,  97. 

salicylate,  101. 
Mica,  79. 

Milch  cows,  needs  of,  267. 
Milk,  291. 

acidity  of,  372. 

antiseptics  in,  296,  297. 

ash  in,  295. 

composition  of,  292. 

deep  setting,  297. 

digestion  of,  261. 

fat  in,  293. 

fertility  in,  230. 

germs  in,  295,  296. 

globules,  294. 

lactic  acid  in,  295. 

powders,  302. 

preservatives,  297. 

secretion  of,  291. 

shallow  setting,  297. 

souring  of,  294. 

sugar,  108,  294. 

yield,  291. 

Mill  concentrates,  270. 
Mixtures,  326. 
Moisture  in  air,  31. 
Molasses,  111. 
Molds  in  fruit,  281. 
Molybdenum,  157. 
Monoses,  108. 
Mordants,  167,  182. 
Morphine,  115. 
Mortar,  90. 
Mosaic  gold,  154. 
Moth  balls,  318. 
Muck,  198. 
Mulch,  209. 

Muriate  of  potash,  119,  222. 
Muriatic  acid,  53. 
Mutton  tallow,  102. 


N 

Naphtha,  91. 

Naphthalene,  318. 

Narcotine,  115. 

Narrow  ratio,  264. 

Negative,  photographic,  150. 

Nernst  lamp,  146. 

Neutralization,  42. 

Neutral  oil,  300. 

Nickel,  ammonium  sulphate,  160. 

coins,  160. 

metal,  160. 

plating,  160. 
Nicotine,  115. 
Nitrate  of  soda,  217. 
Nitrates,  36,  205. 
Nitric  acid,  35,  36,  334. 
Nitrification,  205. 
Nitrites,  properties  of,  37. 
Nitrobenzene,  104. 
Nitrogen,  32,  34,  333. 

cycle,  206. 

fertilizers,  361. 

free  extract,  247. 

in  soil,  356. 

tests  for,  344. 
Nitroglycerine,  106. 
Nitrous  acid,  37. 
Non-metals,  6,  50. 
Nucleoproteins,  114. 
Nut  butter,  282. 
Nutmeg,  283. 
Nutritive  ratio,  264. 
Nuts,  as  food,  272. 
"Nuttolene,"  282. 
Nux  vomica,  115. 


O 

Oatmeal,  277. 

Oats,  270. 

Oil  gases,  93. 

Oil  of  mirbane,  104. 

Oil  of  vitriol,  61. 

Oils,  250. 

drying,  171. 

non-drying,  171. 

solubility  of,  353. 
Oleomargarine,  300,  373. 
Oleo  oil,  300. 
Olive  oil,  102. 
Onion,  278. 


IXDKX 


389 


Open  hearth  process,  165. 

Opium,  115. 

Organic  compounds,  344. 

Osmium,  147. 

Oxides,  acid  forming,  26. 

alkali  forming,  26. 
Oxygen,  24,  331. 
Oxyhydrogen  gas,  327. 
Oysters,  284. 
Ozone,  27,  333. 


Paint,  171. 

enamel,  176. 

stains,  355. 
Palladium,  147. 
Palm  oil,  102. 
Paper,  105. 
Paraffin,  91. 
Paris  green,  71,  309. 

test  for,  374. 

use  of,  310. 
Pasteur  filters,  18. 
Pasteurization  of  milk,  296. 
Peanuts,  277. 
Pearlash,  121. 
Pearl  barley,  276. 
Peat,  formation  of,  198. 
Peat  bogs,  197. 
Pectins,  250,  367. 
Pepper,  283. 
Pepsin,  114,  260. 
Peptones,  114. 
Permanent  white,  129. 
Peruvian  bark,  115. 
Petroleum,  91. 
Petroleum  ether,  91. 
Pewter,  154. 
Phenol,  103. 
Phenolates,  103. 
Phosphate  of  lime,  218,  220. 
Phosphate  rock,  66,  132,  218. 
Phosphates,  339. 
Phosphor  bronze,  152. 
Phosphorus,  cycle,  68. 

in  fertilizers,  70. 

in  soils,  207,  356. 

occurrence  of,  66. 

red,  69. 

yellow,  69. 

Photographic  plate,  149. 
Photography,  150. 


Photography,  developers  in,  104. 

Physical  change,  5,  326. 

Pig  iron,  163. 

Pigments,  174. 

Pink  salt,  154. 

Pintsch  gas,  93. 

Pitchblende,  138. 

Plant,  stem  of,  244. 

Plant  food,  244. 

in  crops,  202. 

in  urine,  362. 
Planting  of  seeds,  358. 
Plant  life,  238. 
Plants,  as  soil  formers,  197. 

carbon  in,  365. 

nitrogen  in,  366. 

potassium  in,  367. 
Plaster  of  Paris,  131,  348. 
Platinum,  146,  147. 
Plumbago,  82. 
Poisons  for  pests,  307. 
Poppy  seed  oil,  171. 
Porcelain,  144,  145. 
Portland  cement,  133. 
Positive,  photographic,  150. 
Potash,  118. 

caustic,  120. 

fertilizers,  221,  360. 

red  prussiate  of,  167. 
Potassium,  118. 

bromide,  122. 

chlorate,  122. 

chloride,  121. 

cyanide,  122. 

hydroxide,  347. 

in  soils,  208. 

iodide,  122. 

metallic,  123. 

nitrate,  121. 

permanganate,  160. 

phosphate,  122. 

platinic  chloride,  147. 

silicate,  122. 

test  for,  347. 
Potato,  277. 

Potato  scab,  treatment  of,  98. 
Potato  starch,  248. 
Producer  gas,  87. 
Proteids,  114. 
Protein,  coagulation  of,  349. 

digestion  of,  262. 

preparation  of,  345. 

test  for,  344. 


390 


INDEX 


Proteins,  114,  252. 

digestibility  of,  272. 

of  rye,  270. 

of  wheat,  270. 
Protoplasm,  238. 
Prussian  blue,  174. 
Prussic  acid,  123. 
Ptomaines,  114. 
Ptyalin,  259. 
Puddling,  210. 
Puddling  process,  164. 
Pulses,  277. 
Putrescine,  114. 
Putty,  130. 
Pyrethrum,  310. 
Pyrite,  166. 
Pyrogallic  acid,  104. 
Pyrogallol,  104. 
Pyroligneous  acid,  98. 


Q 


Quartz,  79. 
Quartz  glass,  77. 
Quicksilver,  152. 
Quinine,  115. 


R 

Radish,  278. 
Radium,  138. 
Rain,  10. 
Rare  earths,  146. 
Reaction  of  soil,  357. 
Red  ocher,  161,  174. 
Rennet,  300.      ' 
Rennin,  260. 
Renovated  butter,  300. 
Reverted  phosphate,  22. 
Rhigolene,  91. 
Rhodium,  147. 
Rice,  272,  276. 
Rochelle  salt,  108. 
Rock,  weathering  of,  192. 
Rock  candy,  109. 
Rock  phosphate,  207. 
Root,  action  of,  242. 
Root  hairs,  242. 
Root  nodules,  206. 
Roots,  277. 

Roquefort  cheese,  302. 
Rosin,  173. 
Rubber,  186. 


Rubber,  black,  188. 

blue,  188. 

coats,  188. 

hard,  189. 

Para,  186. 

plantations,  186. 

preparations,  187. 

red,  188. 

solubility  of,  354. 

substitutes,  189. 

synthetic,  189. 

vulcanized,  188. 

white,  188. 
Rubies,  140. 
Rum,  101,  112. 
Rutabaga,  278. 
Ruthenium,  147. 

S 

Saleratus,  127,  274. 
Sal  soda,  125. 
Salt,  common,  123. 

definition  of,  49. 

preparation  of,  336. 
Saltpeter,  121. 
Salts,  examples  of,  50. 

Epsom,  66. 

in  soil,  358. 
San  Jose  scale,  311. 
Sand,  192,  198. 
Sand  dunes,  195. 
Sand  paper,  77. 
Sapphires,  140. 
Sap,  movement  of,  244. 
Science,  definition  of,  1. 
Seeds,  air  for,  365. 

behavior  of,  241. 

mutilation  of,  365. 

phosphorus  in,  366. 
Serpentine,  79. 
Shellac  varnish,  176. 
Ship's  biscuit,  274. 
Shoddy,  182. 
Shot,  72. 

"Shredded  wheat,"  276. 
Siderite,  161. 
Silage,  252,  288. 

acids  in,  290. 
Silica,  76. 

Silicates,  insolubility  of,  340. 
Silicon,  76. 

dioxide,  76. 


INDEX 


391 


Silk,  180. 
Silt,  198. 
Silver,  148. 

bromide,  148. 

chloride,  148. 

iodide,  149. 

nitrate,  148. 

plating,  150. 

sterling,  148. 
Skim  milk,  297,  299. 
Skim  milk  cheese,  302. 
Slag,  163. 
Sleet,  32. 
Smalt  glass,  161. 
Smokeless  powder,  36. 
Snow,  32. 
Soap,  92. 

calcium,  102. 

hard,  102. 

making,  251. 

soft,  102. 
Soapstone,  79. 
Soda,  125. 
Soda  water,  88. 
Sodium,  acetate,  100. 

action  on  water,  331. 

benzoate,  104. 

bicarbonate,  274. 

carbonate,  125. 

chloride,  123. 

hydroxide,  125. 

iodate,  128. 

metallic,  123. 

nitrate,  127. 

silicate,  77,  128,  340. 

sulphate,  128. 

sulphite,  128. 

test  for,  347. 

thiosulphate,  128. 
Soft  coal,  84. 
Solder,  154. 
Solvay  process,  126. 
Soil,  191. 

acids  in,  207. 

classes  of,  198. 

color  of,  212. 

composition  of,  200. 

drainage,  359. 

fertility  of,  202. 

formation,  192. 

liming,  207. 

sedentary,  194. 

temperature  of,  212,  359. 


Soil,  transported,  194. 

water,  209. 
Spices,  283. 

Spirits  of  hartshorn,  38. 
Spirits  of  wine,  98. 
Springs,  sulphur,  66. 
Stannic  chloride,  154. 
Stannous  chloride,  154. 
Starch,  88,  107,  247. 

action  of  saliva  on,  368. 

effect  of  heat  on,  370. 

grains,  370. 

in  seeds,  245. 

paste,  107,  248. 

preparation  of,  345. 

solution  of,  368. 

test  for,  346. 
Starter,  301. 
Stassfurt  fertilizers,  222. 

salt  beds,  121. 
Steel,  165. 

hardening  of,  165. 

tempering  of,  165. 
Steinholz,  137. 
Stomach,  of  cow,  260. 

of  horse,  260. 
Stomachic  poisons,  308. 
Storage  battery,  155. 
Straws,  288. 
Strontium  nitrate,  130. 
Strychnine,  115. 
Styptic  cotton,  167. 
Sublimate,  corrosive,  153. 
Sucrose,  108. 
Sugars,  108,  249. 
Sugar  beet,  278. 
Sugar,  in  plants,  245. 
Sugar  of  lead,  156. 
Sugar,  manufacturing  of,  110. 

test  for,  346. 
Sulphates,  62. 
Sulphate  of  potash,  222. 
Sulphites,  63. 
Sulphur,  cycle,  66. 

dioxide,  59,  338. 

disinfectant,  317,  318. 

ethers,  103. 

flowers  of,  59. 

in  animals,  64. 

in  plants,  65. 

in  soils,  208. 

occurrence  of,  59. 

properties  of,  338. 


392 


INDEX 


Sulphur,  roll,  59. 

springs,  66. 

trioxide,  61. 
Sulphuric  acid,  338. 

contact  process,  62. 

lead  chamber  process,  62. 

Nordhausen,  63. 

properties  of,  62. 

preparation  of,  61. 
Sunlight  as  disinfectant,  319. 
Superphosphate,  68,  207,  220. 
Swiss  cheese,  302. 
Sylvite,  119. 
Symbols  of  elements,  43. 
Synthesis,  48. 


Talc,  137. 
Tannin,  167,  183. 
Tartaric  acid,  274. 
Tea,  282. 

stains,  356. 

Theories,  definition  of,  2. 
Thermite,  142. 
Thorium,  146. 
Tilth,  208. 
Tin,  foil,  153. 

plate,  153. 

stone,  153. 

Tobacco  decoctions,  313. 
Trypsin,  262. 
Tubers,  277. 
Tungsten,  157. 

electric  lamps,  157. 
Turnbull's  blue,  167. 
Turnip,  278. 
Turpentine,  174. 
Type  metal,  71. 

U 

Ultramarine,  146. 
Ultramarine  blue,  174. 
Urea,  206. 
Uric  acid,  206. 


Vacuum  pans,  111. 
Varnish,  175. 
Vaseline,  91. 
Vegetables,  fresh,  269. 
Verdigris,  152. 


Vermilion,  153,  174. 
Vinegar,  41,  99,  283. 
Vitriol,  green,  166. 

oil  of,  61. 

white,  159. 
Vulcanite,  189. 

W 

Washing  soda,  126,  343. 
Water,  chlorides  in,  337. 

cleansers,  16. 

composition  and  uses,  8. 

distilled,  10. 

drinking,  14. 

electrolysis  of,  8,  327. 

for  plants,  202. 

gas,  86. 

germs  in,  17. 

glass,  77. 

hard,  15,  102,  329. 

in  animals,  13. 

in  plants,  328. 

in  plants  and  animals,  11. 

mineral  matter  in,  15. 

occurrence  of,  328. 

pollution  of,  18. 

purification  of,  19. 

saline  matters  in,  9. 

soft,  329. 

spring,  14. 

well,  14. 

Waterhouse  test,  374. 
Well  water,  salts  in,  327. 
Welsbach  lamp,  87. 
Wheat,  270. 
Whisky,  101,  112. 
White  arsenic,  71,  309. 
White  lead,  156. 
White  vitriol,  159. 
Whitewash,  317. 
Whiting,  130. 
Wide  ratio,  264. 
Wind,  action  of,  159. 
Wines,  101. 
Wintergreen  oil,  101. 
Wolff-Lehmann  standard,  264,  265. 
Wood  alcohol,  98. 
Wood  ashes,  222. 
Wood's  metal,  72. 
Wool,  180. 

burning  of,  353. 
Wool  waste.,  217. 


INDEX 


393 


Working  animals,  needs  of,  266. 
Wounds,  cauterizing  of,  148. 
Wrought  iron,  164. 


Yeast,  371. 

in  food,  273. 

in  fruit,  279,  280. 
Yellow  ocher,  161,  174. 


Zenoleum,  318. 
Zinc,  157. 

chloride,  159. 

oxide,  159. 

oxide  ointment,  159. 

sulphate,  159. 

white,  159. 


;HE  following  pages  contain  advertisements  of  a 
few  of  the  Macmillan  books  on  kindred  subjefts. 


Warren's  Elements  of  Agriculture 


By  G.  F.  WARREN,  Professor  of  Farm  Management  and 
Farm  Crops,  New  York  State  College  of  Agriculture  at  Cor- 

nell University 

Cloth,  ismO)  4.56  pages,  $/./o  net 


Written  by  Professor  G.  F.  Warren,  who  is  in  charge  of  the  Department  of 
Farm  Management  and  Farm  Crops  in  the  New  York  State  College  of  Agri- 
culture, Cornell  University,  an  authority  on  questions  pertaining  to  practical 
agriculture. 

Professor  Warren  is,  moreover,  a  farmer.  He  grew  up  on  a  farm  in  the  mid- 
dle West  and  is  living  at  the  present  time  on  a  farm  of  three  hundred  and 
eighteen  acres,  which  he  supervises  in  connection  with  his  work  at  the  Univer- 
sity. 

The  "  Elements  of  Agriculture  "  is  a  text  that  does  not  "  talk  down  "  to  the 
pupil.  It  gives  agriculture  rank  beside  physics,  mathematics,  and  the  languages, 
as  a  dignified  subject  for  the  course  of  study. 

In  Warren's  "  Elements  of  Agriculture  "  there  is  no  waste  space.  It  is  writ- 
ten with  the  ease  that  characterizes  a  writer  at  home  in  his  subject,  and  it  is 
written  in  a  style  pedagogically  correct.  The  author  has  been  a  teacher  of  high 
school  boys  and  girls  and  knows  how  to  present  his  subject  to  them. 

Experts  in  the  teaching  of  agriculture  the  country  over  have  been  unanimous 
in  praise  of  the  text.  For  instance  : 

Mr.  J.  E.  BLAIR,  Supt.  of  Schools,  Corsicana,  Texas  : 

"An  examination  of  Warren's  '  Elements  of  Agriculture  '  convinces  me  that 
it  is  a  book  of  uncommon  merit  for  secondary  schools  as  well  as  for  the  private 
student.  It  is  thoroughly  scientific  in  matter,  and  is  written  in  an  attractive 
style,  that  cannot  fail  to  please  as  well  as  instruct." 

Supt.  E.  S.  SMITH,  Whiting,  Iowa  : 

'•  I  am  very  much  pleased  with  Warren's  '  Elements  of  Agriculture.'  In  my 
opinion  it  is  the  only  book  on  the  market  that  presents  the  work  of  agriculture 
suitably  for  high  schools  ;  too  many  books  are  too  simple  and  do  not  give 
enough  work  ;  a  book  for  high  schools  must  be  more  than  a  primer." 


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Practical  Physics  for  Secondary  Schools 

By  N.  HENRY  BLACK  of  the  Roxbury  Latin  School, 
Boston,  and  Professor  HARVEY  N.  DAVIS  of  Harvard 
University. 

Cloth,  i2mo,  illustrated,  488  pages.     TAst  price,  $r.2f 

"  In  preparing  this  book,"  say  the  authors  in  the  Preface,  "  we  have  tried  to 
select  only  those  topics  which  are  of  vital  interest  to  young  people,  whether  or 
not  they  intend  to  continue  the  study  of  physics  in  a  college  course. 

"  In  particular,  we  believe  that  the  chief  value  of  the  informational  side  of 
such  a  course  lies  in  its  applications  to  the  machinery  of  daily  life.  Everybody 
needs  to  know  something  about  the  working  of  electrical  machinery,  optical 
instruments,  ships,  automobiles,  and  all  those  labor-saving  devices,  such  as 
vacuum  cleaners,  fireless  cookers,  pressure  cookers,  and  electric  irons,  which 
are  found  in  many  American  homes.  We  have,  therefore,  drawn  as  much  of 
our  illustrative  material  as  possible  from  the  common  devices  in  modern  life. 
We  see  no  reason  why  this  should  detract  in  the  least  from  the  educational 
value  of  the  study  of  physics,  for  one  can  learn  to  think  straight  just  as  well  by 
thinking  about  an  electrical  generator,  as  by  thinking  about  a  Geissler  tube.  .  .  . 

"  To  understand  any  machine  clearly,  the  student  must  have  clearly  in  mind 
the  fundamental  principles  involved.  Therefore,  although  we  have  tried  to 
begin  each  new  topic,  however  short,  with  some  concrete  illustration  familiar 
to  young  people,  we  have  proceeded,  as  rapidly  as  seemed  wise,  to  a  deduction 
of  the  general  principle.  Then,  to  show  how  to  make  use  of  this  principle,  we 
have  discussed  other  practical  applications.  We  have  tried  to  emphasize  still 
further  the  value  of  principles,  that  is,  generalizations,  in  science,  by  summariz- 
ing at  the  end  of  each  chapter  the  principles  discussed  in  that  chapter.  In 
these  summaries  we  have  aimed  to  make  the  phrasing  brief  and  vivid  so  that 
it  may  be  easily  remembered  and  easily  used." 

The  new  and  noteworthy  features  of  the  book  are  the  admirable 
selection  of  familiar  material  used  to  develop  and  apply  the  principles 
of  physical  science,  the  exceptionally  clear  and  forceful  exposition, 
showing  the  hand  of  the  master  teacher,  the  practical,  interesting, 
thought-provoking  problems,  and  the  superior  illustrations. 


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Botany  for  Secondary  Schools 

BY  L.   H.   BAILEY 

Of  Cornell  University 

Cloth,  izmo,  illustrated,  460  pages.    List  price,  $1.25 

It  is  not  essential  nor  desirable  that  everybody  should  become  a  botanist, 
but  it  is  inevitable  that  people  shall  be  interested  in  the  more  human  side 
of  plant  and  animal  life.  We  are  interested  in  the  evident  things  of  natural 
history,  and  the  greater  our  interest  in  such  things,  the  wider  is  our  horizon 
and  the  deeper  our  hold  on  life. 

The  secondary  school  could  not  teach  botanical  science  if  it  would ;  lack  of 
time  and  the  immaturity  of  the  pupils  forbid  it.  But  it  can  encourage  a 
love  of  nature  and  an  interest  in  plant  study;  indeed,  it  can  originate  these, 
and  it  does.  Professor  Bailey's  Botany  has  been  known  to  do  it. 

In  the  revision  of  this  book  that  has  just  been  made,  the  effective  simplicity 
of  the  nature  teacher  and  the  genuine  sympathy  of  the  nature  lover  are  as 
successfully  blended  as  they  were  in  the  former  book.  Bailey's  Botany  for 
Secondary  Schools  recognizes  four  or  five  general  life  principles :  that  no 
two  natural  things  are  alike ;  that  each  individual  has  to  make  and  main- 
tain its  place  through  struggle  with  its  fellows ;  that  "  as  the  twig  is  bent 
the  tree  inclines";  that"  "like  produces  like,"  and  so  on.  From  these 
simple  laws  and  others  like  them  Professor  Bailey  proceeds  to  unfold  a 
wonderful  story  of  plant  individuals  that  have  improved  upon  their  race 
characteristics,  of  plant  communities  that  have  adopted  manners  from 
their  neighbors,  of  features  and  characteristics  that  have  been  lost  by 
plants  because  of  changed  conditions  of  life  or  surroundings.  The  story 
vibrates  with  interest. 

The  book  is,  moreover,  perfectly  organized  along  the  logical  lines  of 
approach  to  a  scientific  subject.  Four  general  divisions  of  material  insure 
its  pedagogical  success : 

PART     I.  — The  Plant  Itself; 

PART    II.  — The  Plant  in  Its  Relation  to  Environment  and  to  Man; 
PART  III.  —  Histology,  or  the  Minute  Structure  of  Plants ; 
PART  IV.  — The  Kinds  of  Plants,  including  a  Flora  of  130  pages. 


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Shelter  and  Clothing: 

A  TEXTBOOK   OF  THE   HOUSEHOLD   ARTS 

By  HELEN  KINNE,  Professor  of  Household  Arts  Educa- 
tion, and  ANNA  M.  COOLEY,  Assistant  Professor  of  House- 
hold Arts  Education,  Teachers  College,  Columbia  University. 

In  press 

This  book  and  the  volume,  Foods  and  Household  Management,  that  follows 
it,  make  up  a  full  course  in  domestic  matters  not  confined  to  details  of  cooking 
and  sewing.  The  books  treat  fully,  but  with  careful  balance,  every  phase  of 
home-making.  The  authors  hold  that  Harmony  will  be  the  keynote  of  the 
home  in  proportion  as  the  makers  of  the  home  regard  the  plan,  the  sanitation, 
the  decoration  of  the  house  itself,  and  as  they  exercise  economy  and  wisdom  in 
the  provision  of  food  and  clothing. 

"  Home  Economics  stands  for  the  utilization  of  the  resources  of  modern 
science  to  improve  home  life,"  and  to  this  end  homemakers  should  be  con- 
versant with  modern  scientific  thought  on  matters  domestic.  The  best  schemes 
of  heating  and  lighting,  modern  arrangements  for  the  disposal  of  waste,  the 
sanitary  efficiency  of  tinted  walls,  of  bare  floors,  of  furniture  built  on  simple 
lines,  these  are  some  ways  in  which  modern  science  instructs  the  intelligent 
homemaker.  In  the  selection  of  textiles  for  clothing  and  domestic  use,  a 
housekeeper  to  be  efficient  must  be  able  to  distinguish  between  fabrics  of  dif- 
ferent fibers  and  to  choose  durable  weaves,  she  must  be  able  to  detect  adultera- 
tion and  the  deceptive  "  finishing  "  processes.  In  buying  ready-made  garments 
she  must  know  how  to  protect  herself  and  her  family  from  the  danger  of  gar- 
ments infected  by  diseased  operators  in  sweatshops.  The  up-to-date  book  on 
home  economy  treats  such  topics  and  relates  them  to  common  experience. 

The  plan  of  the  book  is  flexible.  Parts  may  be  omitted  or  shifted  to  meet 
the  necessity  or  the  convenience  of  different  schools.  The  chapter  headings 
in  some  measure  disclose  the  breadth,  the  variety,  and  the  practicability  of  the 
book  : 

The  Home.  —  Its  plan  and  construction  ;  heating,  ventilating,  lighting, 
water  supply,  and  the  disposal  of  waste  ;  decoration  ;  furnishing.  Textiles.  — 
Materials  and  how  they  are  made.  Garment-making.  —  Patterns  ;  cutting  and 
making  garments;  embroidery.  Dress. —  History  of  costume ;  hygiene  of 
clothing ;  economics  of  dress  ;  care  and  repair  of  clothing ;  millinery. 


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